and visit our facebook page or youtube channel. thanks for watching. "20/2 "20/20" starts right now. there's no way that michelle would ever take her life. >> the word suicide was thrown around without any investigation. >> i screamed and yelled, we want an outside investigation. >> if she didn't cause her death, who do they think did? >> i'm breaking up with him, starting my life over. >> breaking up with her

boyfriend jeremy, who just happens to be in the sheriff's department. >> i didn't do anything. >> they walked in the door, jeremy told them this is a suicide. everything stopped. >> no one is charged. tonight, we're doing our own "20/20" investigation. >> you had better take the gun out and test it. >> and the family is, too. even exhuming her body. >> she's resting in peace. but i have a desire for the truth. >> it's beyond me how you could miss that. >> oh, my gosh. it seemed obvious there has been a crime against my daughter. >> we were meeting for coffee at a local gas station. the call came over the radio for shots fired.

immediately we jumped up, left the gas station, got in our cars. i wasn't sure what to expect when we got on scene. >> reporter: st. augustine, florida, in 2010. debra maynard was a sheriff's deputy assigned to the southeast part of town. she remembers racing to the scene in response to this 911 call. >> 911. >> hey. please get someone to my house. it's 4700 sherlock place. >> reporter: the call is placed by fellow deputy jeremy banks. >> what's going on? >> please send -- my girlfriend, i think she just shot herself. there's blood everywhere. please! >> reporter: when help arrives, deputies find a scene every bit as grisly as the caller describes. >> walked in around the bar in the kitchen, and i saw some feet of a female prone on the floor there. >> reporter: the victim is jeremy banks' girlfriend, 24-year-old michelle o'connell. she's got a gunshot wound to the

head, and dozens of prescription painkillers in her pocket. >> and i looked across the room, and the deputy in question, jeremy banks, was crouched at the bathroom door, just squatting there, holding a phone in his hand. >> reporter: a deputy is instructed to snap these photos to document the scene before emts begin lifesaving measures. the weapon sits to her left, the tac light on the gun is in the "on" position. the pictures also reveal a separate shot fired into the carpet. despite the efforts of first responders at the scene, michelle o'connell is pronounced dead at 11:48 p.m. outside the home, some deputies and detectives begin to reach a conclusion. this was a woman who took her own life. some of them were later interviewed as part of the investigation. >> i didn't have any suspicions that it was anything other than suicide. i think that's what we were all

kind of discussing, but just making sure that we covered our bases. >> it appeared she had committed suicide. >> reporter: fellow deputies take time to console a co-worker, a friend, in his time of need. >> i went up to jeremy, just, you know, asked him if he was okay, and i, you know, advised jeremy that, you know, i'm here for him, anything he needs. >> reporter: a squad car is used as a makeshift interview room to question the 23-year-old banks. that interview is recorded by a detective. >> all right, this is detective hines. it is officially september 3rd at 1:23 in the morning. you were outside in the yard, driveway? >> my motorcycle's in the garage. i was sitting on it, and i heard a pop, and i knew exactly what it was, and i ran inside. i started screaming her name. the bedroom door was locked, and i screamed her name again. i heard it go off again a second time. >> reporter: a sad story for sure, but not a headline-grabbing one in st. augustine. >> no, i mean, it wasn't really a story.

it hadn't been reported anywhere ever. there was no story about it before the one we did. >> reporter: all that's left to sherriff's deputies to do now is inform the o'connell family of the tragedy. >> they just said that she committed suicide, your daughter killed herself. she committed suicide. >> i said, this is [ bleep ]. there's no way that michelle would ever take her life. >> reporter: michelle o'connell, a single mom, was working two, sometimes three jobs to support a 4-year-old daughter, alexis. >> michelle had alexis, and her whole life changed. she just lived for alexis. some people are just meant to be mothers, and michelle was meant to be a mother. >> she was devoted. there's no way. who would take care of alexis? >> reporter: michelle's life was looking up after she landed a dream job at a day care center. teresa woodward was the director who gave her the job.

>> i took her over to the vice president's office to get her key. it's a very prestigious thing to be honored, to be respected, to be trusted to have a key to a whole building, and michelle was so excited. >> reporter: it was literally and figuratively the key to her future. >> she was so elated that she had a job that was a career. she said, i'm going to the doctor and i'm not even sick, but i have insurance for once in my life. >> reporter: but on the very day michelle was set to start her life-changing position -- >> i got a phone call that said that michelle had died. i said, no. >> reporter: o'connell's brother and sister say the family's grief turned to frustration once they realized the sherriff's department spent just a few hours at the scene before calling michelle's death a suicide. >> i mean, the word suicide was thrown around right off the bat without any investigation. >> and i screamed and yelled at

the top of my lungs, we want an outside investigation. >> reporter: but two days later, the medical examiner, dr. frederick hobin, performs an autopsy, and officially rules her death a suicide, and the sheriff says no to an outside investigation. david shoar is powerful, political, and protective of the men and women on his force. >> this is just a sheriff that's out of control, and a situation that was mishandled, and then at the root of it a family that suffers because of egos and power. >> reporter: shoar is a career lawman. and an elected official. he's so well-connected, he often runs and wins unopposed. but now he finds himself facing stiff opposition from the victim's family and friends. >> i think jeremy killed her. >> reporter: even more stunning, debra maynard, who was at the scene that night, agrees. and for you, that's murder? >> it is murder.

>> reporter: when we return, what does the family know about the relationship between michelle and jeremy? and, tracking michelle. the last 90 minutes of her life. what happened? foundation. true match from l'oreal. seamless, flawless coverage in 45 shades. find your true match. it truly matches my skin. true match is enriched with 80% moisturizing serum yet is lightweight, super-blendable. it means when i wear makeup... it enhances me. with true match... i can't tell where my foundations ends... ...and where my skin begins. find your true match. 100% guaranteed. from l'oreal paris. because we're worth it. ♪ i planned each charted course ♪ ♪ each careful step ♪ along the byway ♪ much more ♪ much more than this ♪ i did it my way

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>> reporter: through various interviews, the last hours of michelle o'connell's life in florida can be put on a timeline. it begins with a concert here at the st. augustine amphitheater. it's a hot, sticky night and a packed house as the curtain is about to go up for the band paramore. the curtain, however, is about to come down on michelle and jeremy's relationship. as the band plays their hit

"misery business," jeremy and michelle are caught up in their own misery. fighting has become all too common. the couple had words before, during, and after the show. >> yeah, we don't get along. we fight all the time. i mean, it's never -- never bad fighting, it's always just arguing. >> reporter: but having purchased seats in advance, michelle decided to see the show and then call it quits with jeremy. >> she said, in true michelle fashion, "i paid for the tickets, i'm going. i'm breaking up with him, i'm starting my life over." and, you know, i'm more sensitive and she said, "i'll be fine." >> reporter: michelle's brother sean was seated with the contentious couple and describes jeremy this way. >> just kind of withdrawn and as the night went on, you know, i was like, well, i'm here with my sister and this guy's being like debbie downer over here. i was like, "hey, do you mind scooting over, if you're not going to have fun at the concert with my sister, i'm definitely going to." >> reporter: this photo was taken of a subdued banks at the

show. michelle is all smiles with her brother. hours earlier, she had lunch with her sister. >> i had met michelle for lunch at my place. and we were talking about her looking for a new apartment. that she was breaking up with jeremy. this was kind of a culmination. i was concerned with all the violence and the -- how the relationship had turned. >> reporter: there were whispers of verbal and physical abuse from both sides. >> she said, "there's going to be a fight because he's going to want me to go out after the concert." and i said, "don't even go to the concert." because i knew jeremy was rageful. i knew in my heart something was gonna happen. >> reporter: something is happening. sister chrissy begins receiving curious text messages from michelle at the concert. "promise me one thing. lexi will be happy and always have a good life." "promise you what?" "that no matter what, lexi will always be safe and loved." "what's going on?"

"i'm scared." it seems like a mixed message. someone saying a final good-bye? or someone who feels danger may be coming their way? as the concert lets out, michelle alerts chrissy, who is watching michelle's 4-year-old daughter. "i'll be there soon." it is an appointment michelle will not keep. after the show, the couple begins to drive home. that's when michelle informs jeremy it's over. >> that's whenever she said, "i'll have my things out by this weekend." and i said, "are we breaking up?" she said yes. and i was, like, "all right." and we were talking about it. i raised my voice. she raised her voice. we argued. but when we got to the house, we were fine. >> reporter: according to jeremy, michelle is inside while he remains outside with two friends who stopped over after the concert. michelle comes outside to retrieve a make-up bag from the car and quickly returns. after 10 to 20 minutes, the friends leave. jeremy says he's alone in this garage. >> i heard it pop and i knew exactly what it was.

just instinct and i just said [ bleep ]. >> reporter: what happens and what does not happen in the hours that follow troubles former fbi agent brad garrett. >> when you get to a small department, you're really talking about people you're friends with. and so you need a level of objectivity in those interviews. >> reporter: objectivity that may have been lost, says garrett, shortly after help arrived. >> i think they walked in the door, jeremy told them, fellow officer, "this is a suicide," everything stopped. >> reporter: do you just take a guy's word for it? >> of course not. and the only way you find that out is to treat this scene like it's a homicide until you prove it otherwise. >> reporter: that was not done in this case according to debra maynard, who was fired by the sheriff reportedly for untruthfulness. maynard claims it was because the sheriff asked her to lie in an unrelated case and she refused. >> we were told it was a suicide. they automatically said it was a suicide, though we are trained to say every scene is a homicide until proven otherwise.

>> reporter: 12 days later, banks is in the sheriff's office for another interview. >> he's not treated like a suspect, but a friendly colleague. >> comfy spinning chair, not the suspect chair. >> reporter: jeremy blurts out an admission, revealing he's gained access to a sheriff's report on this case. >> i've already read the report. i know i probably shouldn't have. i just wanted to know what went down on the other side. >> reporter: a detail the detective seems to gloss over. >> you know that's only been -- tell me the basics. tell me what you -- where you saw things. >> how in the hell does jeremy get to review the report before he's interviewed by his peers. this is crazy. >> reporter: some in the department would later admit to having doubts that night. >> when i first walked into that room, the first thought that went through my mind was, "this is not good for jeremy." >> reporter: former deputy debra maynard is even more critical of the sheriff's department.

scale of 1 to 10, 10 being a great job on an investigation. where would you rate this? >> 1. >> reporter: the sheriff would later acknowledge missteps were made. among the missteps, deputies failed to canvass the neighborhood for witnesses. deputies failed to interview the decedent's family members. deputies failed to isolate, interview, and photograph banks in a structured environment. and what about jeremy? could he have done more? attorney mac mcleod represents jeremy banks. he busts in the room, she has shot herself, he's calling 911, "get over here, get over here." >> right. right. >> reporter: wouldn't it occur to him as a deputy, take her pulse, perform life-saving measures, do everything he can to try to save her life. >> i don't think his frame of mind was as a deputy at the time as i was saying. i think his frame of mind was just completely shocked and freaked out. >> reporter: but the o'connell family says none of this makes any sense. she wasn't looking to take her

life. in fact, she was looking to save a life. her appointment book, found in the car, shows michelle had signed up for cpr training two days after her death. and remember those pills found in michelle's pocket? they were from jeremy's prescription bottle. none were found in her system. all the pills were accounted for. and keep in mind, she was looking for her makeup bag minutes before her death, and had plans to meet up with her friend mindy fox. >> she was like, you're not going to flake on me, are you? we're still hanging out tonight, right? and i was like, yes. we're still hanging out. and she was like, good. >> reporter: it took four months but sheriff shoar finally bows to family pressure knowing his investigation fell short. he asks state investigat take a fresh look at the case. to find out what happened on sherlock place, the state calls on their own version of sherlock holmes.

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>> reporter: thanks to spanish explorer ponce de leon, the fountain of youth has been a must-see attraction in st. augustine for years. but upon closer inspection the legendary fountain is actually akin to a minor water main break. some things are simply not what they appear in st. augustine. that's the mindset of chrissy o'connell, who has to fight every day to remind people her sister did not commit suicide. >> we had to fight, rally, protest, blog, everything we could think of, just to get fdle to come in, which should've been done day one. >> reporter: the family now has an outside investigator to look into their suspicions.

>> i'm special agent rusty rodgers with the florida department of law enforcement. >> reporter: rusty rodgers finds something the sheriff's office did not. two women with good hearing. their account was featured in a documentary produced by "frontline" and "the new york times." >> we heard a woman yell for help, we heard a gunshot. and then there was another yell for help and then another gunshot. >> and then there was silence? >> and then there was silence. there was no commotion, no nothing. it seemed like a long -- it was probably ten, maybe 15 minutes, and the sirens came. >> reporter: the sheriff says it is not uncommon for some suicide victims to fire off a test shot before the fatal shot. >> if she was suicidal, if she was killing herself, she's not gonna scream for help. >> reporter: rodgers takes his findings to the medical examiner's office. dr. frederick hobin is persuaded by the earwitnesses. the medical examiner, who did not want to go on camera when approached by jacksonville reporter anne schindler, did allow the audio of their conversation recorded.

>> the fdle did a pretty thorough job, i thought. >> and so at that point you became convinced that it was what? >> well, i became convinced that it was probably a homicide. >> reporter: medical examiners don't make decisions solely based on the body in front of them. much of what they learn about the case is through conversations with investigators. after listening to rodgers' presentation in june of 2011, dr. hobin fills out an amended death certificate and lists homicide as the manner of death. listen. >> i had a state attorney investigator here as a witness, and i said based on this i would amend the autopsy, and change the manner of death from suicide to homicide. well, i did that, but just internally. i didn't send it out. it wasn't filed with anybody, wasn't sent to the funeral director.

wasn't disclosed to anybody except the state attorney. >> reporter: hobin says he was told to hold off filing the document by the state attorney while the investigation continues. >> we had people almost, almost close to doing the right thing, and then we have people above them that said, "no, we're going to do it a little different." >> reporter: hobin never officially files that amended certificate. he's later reprimanded by the state for keeping that document at his home. eventually a new medical examiner is consulted, one who will turn this investigation upside-down. in the "frontline" documentary, dr. predrag bulic believes the death was a suicide and presents an alternative theory. the gun used was upside-down at the time it was fired. this, he says, would help explain a second wound, this cut above michelle's eyelid. >> why don't you show us how you believe she held the gun when she shot herself. >> this is the way that i

believe the suicide occurred. >> reporter: as the fdle agent rusty rodgers continues his investigation, he goes face to face with jeremy to see who blinks first. neither man does. >> i'm concerned. >> this is a yes or no question. if you say yes, we're done. >> reporter: he interviews her 5-year-old daughter, alexis. >> what does jeremy do that is bad? >> he jumped on her and hits her. >> what did jeremy use to hit your mommy? >> a belt. >> did you see that happen one time or more than one time? >> one time. >> and i heard you say that

jeremy jumped on your mommy to hurt her? >> uh-huh. >> what did your mommy say when that happened? >> stop, stop, but he wouldn't stop. >> reporter: jeremy said he only restrained her when she ran at him. testing is done to see if michelle shot herself, or was shot by someone else based on where the shell casings landed. his conclusion -- this was a homicide. but special prosecutor brad king, who is now assigned to the case, reviews all the investigations and reaches a conclusion. >> he calls us in for a meeting and basically says, "there's not enough evidence." so our family was just pushed aside. my mom was devastated, and i think i've said before it was the second worst day of my life. you know, the first, losing michelle. >> reporter: sheriff shoar pens a 152-page review of the case, a

mostly positive assessment of the department's work. >> this is a case where there's not going to be a happy ending. >> reporter: but he also tears into that shell casing test ordered by rodgers for being conducted in an open field. one that he says did not take into account the variables at the scene such as the walls, ceiling, furniture, and michelle's extremities. banks will also fight back in the form of a lawsuit against the fdle and rodgers for allegedly violating his civil rights. the case will drag on for years. >> they investigated, their, themselves, and then later on they finally bring in fdle, who paints this picture that it's not jiving, it doesn't look good, and they don't like it. so they attack the fdle agent and go after him hard. tooth and nail. >> reporter: when we return, the search for clues. from a gun range to a graveyard.

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>> reporter: 1,000 miles from the ugti lighthouse, a pennsylvania forensic scientist is trying to shed some light on the curious death of michelle o'connell. today we've come to roll call, an indoor shooting range in scranton, to examine two key points in this investigation. using dr. bulic's theory, we want to see where the shell casings may land when the gun is upside-down, and see whether an upside-down gun, once fired, could have caused the injury above michelle's eye. sheriff shoar has been critical of the outdoor crime scene reconstruction by the fdle. so today we are going inside. we've created a replica of the scene based on scene photos.

we use a mannequin for the purposes of this test. and you can see this is the layout of the bedroom, door right here, people came in and out of the room this way. we ask professor peter diaczuk, a forensic scientist at penn state, to conduct a firing test for us. back in 2013 diaczuk reviewed the case for a "frontline"/"new york times" investigation. professor, how well do you know the gun that was used in this case? >> i am familiar with the, with the firearm. >> reporter: have you fired that gun before? >> many, many times. >> reporter: in those initial set of photographs taken at the scene, there's no visible sign of any shell casings around michelle's body, but two were later clearly photographed to her left in this back corner of the bedroom. this bag right here was where a shell casing was found, another one found about 18 inches away. >> the location of the spent cases is going to be dependent upon several factors. one of the most profound is the position of the firearm when it

was fired. >> reporter: we'll be using the same make and model of the gun that fired the fatal shot plus live rounds. >> to keep those rounds under control, we're going to be firing into ballistic gelatin. >> reporter: at the end of the day, what is it that you want to find out? >> we're going to see with our documentation where the cartridge cases will land depending on the position of the firearm. >> reporter: you're going to be holding that gun upside-down and firing it. why is that? >> that's because we are going to be replicating the position of the firearm as dictated by the reports, and the interviews of the medical examiners. >> reporter: all right. be safe. we walk about 15 yards to observe the firing test behind bulletproof glass. the mannequin is laying down. >> the most likely set of circumstances is that she was lying on the ground, pulled the gun up, probably two-handed and fired, and then the blood does exactly what is seen in the pictures, and goes this way. >> see how he's holding it? upside-down is the way

authorities say she held it. [ gunfire ] >> that's loud. >> reporter: using high-speed photography, you can actually see the shell casing ejecting towards the right side of the mannequin. that is on the opposite side of where the shell casings were found at the scene. see those casings coming this way? each time, this way. [ gunshot ] again. [ gunshot ] where did authorities find those casings? on the other side, where the professor is. let's go talk to him. okay, professor. how many shots did you just fire? >> i fired ten cartridges. >> reporter: so we have nine over here, one right here under her knee. >> that's correct. >> reporter: so if she's lying down, holding the gun like that, there's no way that if she fired those shots that those casings would land over here? >> that's correct. it just doesn't conform to the physics of the way the firearm is designed. >> reporter: sheriff shoar has an explanation. those shell casings could have been inadvertently kicked by any one of nine first responders at

the scene. so let's take a look at this. we bring in roll call owner joseph harris, a retired corporal with the scranton police department, who's worked hundreds of crime scenes over his career. based on what you see here, how possible is it that a casing that ends up on this side of michelle ended up all the way over there? >> it's a far distance. >> reporter: how likely is it that a casing would've been kicked from here all the way over to there? >> i would say not, not so likely. >> reporter: ten bullets ready in the clip. we reset. now you see that the dummy is sitting up. that's the other way that authorities said, in their mind, that michelle might have killed herself. [ gunshots ] casings coming this way. looks like almost every casing came to the right of michelle. next, we position the mannequin in a kneeling position.

another possibility of how michelle might have shot herself. ten more shots, and this time we learn the sheriff is right about one thing. objects in the room can play a role in where the casings land. so you've now fired 30 shots, three different positions. based on the way you shot, what are the chances that a shell casing would end up over here? >> incredibly unlikely. >> reporter: this being right here, perhaps it could've been kicked there, but is there a contrary argument to that? >> the contrary argument would be if the direction of travel of the responders is to attend to the victim, and the door is in that part of the building, then it would be more likely that it would be kicked in the same direction that they're traveling, which is to the right of the victim. >> reporter: while our test raises questions about dr. bulic's upside-down gun theory, it does not prove or disprove that it was suicide or homicide. michelle's family is convinced someone else was holding the gun.

so what would happen if the professor stood over michelle and shot down towards her? not the gun turned upside-down anymore, but just straight away. [ gunshots ] the cartridge cases were ejected from the firearm and created a pattern on the victim's left. >> reporter: what's interesting is there's a shell casing all the way over here, and this is just a couple of, what, maybe couple of inches away from where one of the casings was found. is it more likely that she was impacted by this gun in the way that the police described it, or in the way that the family believes, which is jeremy shot her? >> our experimentation clearly reveals that the family's scenario is the more likely scenario. >> reporter: we showed michelle's mom patty the results of our firing test. >> why wouldn't the sheriff take the time to do a test? i see it and i go, she did not kill herself, and that's what i feel. >> reporter: but feelings are not facts.

there's one more thing we wanted to examine. remember michelle's eyelid injury? dr. bulic told "frontline" it was the tac light that caused that injury. >> the only sound, solid forensic explanation is that the gun was upside-down and the tactical light caused that. >> reporter: to the experts out there that say that when you fire a gun like that, that the gun would not go up but instead would go back, that it would recoil backwards. not so, says jeremy's attorney. >> what do i say to those experts, unnamed or named, i'd say you better take the gun out and test it before you say that. >> reporter: but that's exactly what professor diaczuk did. and using high-speed photography you can clearly see the gun going backwards and flying away from what would have been michelle's face. >> firearms do not go forward upon firing. it's against the laws of physics. >> if you measure the arc of the tac light, and you measure the

arc of the wound, they are awfully consistent. the tac light may have done that in an antemortem event, but it did not happen at the moment that the firearm was fired. >> reporter: in other words, diaczuk says it could have happened before the fatal gunshot. but special prosecutors embraced bulic's theory, and determined there was not enough evidence to charge jeremy with a crime. so if that gunshot didn't cause the eye injury, what did? when we come back, michelle gives her family a clue right from the grave. stay with us.

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>> reporter: besides her then-boyfriend deputy sheriff jeremy banks, only michelle o'connell knows what truly happened when those two gunshots were fired that september night. but was there more they could learn from exhuming michelle's body? >> patty o'connell was waiting for the state agency to do it themselves. she gave them permission and then they never did. >> it's hard. she's resting in peace. but i just had this, a desire for the truth. why would they ask me to exhume her and then not exhume her? >> and so obviously the family felt strongly enough about it that they decided to do it themselves. >> reporter: the o'connells get in touch with dr. william anderson, a forensic pathologist and former deputy chief medical examiner for >> i was asked to examine the utopsy. on michelle and then >> reporter: while examining

the original autopsy, something in an x-ray gets dr. anderson's attention. >> there was some indication that there was some other injury on the body, so when we did the exhumation, the jawbone was in two pieces so that indicates there was a fracture. >> reporter: a fracture that comes as a surprise to the family and most anyone following the case. >> now to new developments in a deadly mystery. >> reporter: dr. anderson's findings make national headlines. >> the family points to a new autopsy. >> reporter: and as soon as st. john's county sheriff david shoar learns about the exhumation, he goes on the attack and issues a scathing statement about the family. >> he has gone on to say that our family's basically paying someone to author a report for us, so we'll feel better, which isn't the case. >> despite rumors and statements to the contrary, we did this totally pro bono. >> reporter: in that statement, the sheriff goes on to say, "molesting michelle from her place of rest using some freelance type approach is beyond unconventional, it was reprehensible." >> to the sheriff, i say, "[ bleep ] you." because he has no right, even if

he doesn't agree with it, or whatever, he should in no way, shape, or form ever speak, public release, whatever, to a family using those words, ever. it really shows his character. >> reporter: and news of the fracture brings into question the work of the original medical examiner, dr. hobin. there's a fracture right there. >> right. >> reporter: now, this was never on the autopsy report. >> the x-rays, it just jumps out at you. it's beyond me how you could miss that in the original autopsy report, because that is a big deal. >> reporter: so the fact that it's not on that report, what do you attribute that to? >> i think this was just sloppy. i think that the police said it's a suicide, well, it could well be a suicide. and just sort of write it off and keep going. >> reporter: but jeremy banks' dr. hobin was aware of michelle's jawbone fracture, even though it's not depicted in this autopsy sketch. >> in his notes he has noted mandibular separation. it's not in the autopsy report, it's in his field notes. >> well, that, yeah, that's very

disturbing actually, too, because if everything else is very carefully described, and you leave out a major finding out of your report, it's not good practice. >> i'm not an expert on fractures, but even i could see, i go, "oh, my gosh, her jaw's broken." >> when you're the family and you've got as many questions as they do, anything like that is going to seem incredibly suspect, right? "why didn't we know she had a broken jaw?" that does seem significant. >> reporter: significant not only because it was not reported in the autopsy report, but more importantly for what dr. anderson says it reveals about how michelle died. >> the only explanation that i can see that's reasonable is that there was another force, a blow to the chin that broke the mandible prior to the time the gunshot wound was inflicted. in my opinion, it was a homicide. >> reporter: jeremy banks has always denied hurting michelle the night of her death and he has never been charged with a crime. >> what the family wants to believe or what the theory wanted, being proposed was is that she must have been hit

really hard. well, there's a problem with that. there's no m.e. worth his salt that will tell you that in an intraoral gunshot wound such as this with a high-powered weapon that more often than not you expect to see mandibular separation. >> reporter: it is possible in some cases that a shot could split the jaw. but dr. anderson says that's not the case with michelle, based on the evidence he reviewed. >> there was a gunshot wound to the mouth that put a hole in the tongue, but didn't do any other damage to the teeth, to the gums, to the floor of the mouth, the very soft tissue that basically would've been destroyed if there had been enough force from that blast to break the jaw. >> if she had been hit, you would see bruising, you would see abrasion, you'd see something. there's nothing. >> i've probably done 8,000 or 9,000 autopsies. if you die quickly enough, you will not have bruising. >> reporter: having gotten the answers the family was looking for, michelle is returned to an open grave. but her death is still an open

question to the family. in 2017, the florida medical examiners' commission reprimanded dr. hobin and dr. bulic, a small vindication for the o'connell family. >> they determined that they had mishandled some of the components of the investigation. for hobin, was that he brought some material home and hadn't kept it in the medical examiners' office. >> reporter: including michelle's amended death certificate. >> and then bulic, i think, had just showed autopsy photos that he wasn't supposed to show to non-family members. >> reporter: dr. hobin was also called out for his poor recordkeeping, failing to document the jawbone fracture in his autopsy report. the medical examiners and state attorney all declined to comment for this story. in a statement, the sheriff's office told us, "this case has been extensively reviewed by numerous investigators," who "have continually ruled the death a suicide." based on as things stand right now, do you think it's possible to prosecute jeremy banks for murder? >> it doesn't sound like you're going to be able to do it in the

state of -- >> reporter: why not? >> -- florida. well, i mean, how many state's attorneys have looked at this case? >> reporter: so you think this case isn't prosecutable at this point? >> it doesn't appear that it would be prosecutable in st. john's county, florida. >> reporter: next, a development in the case gives new hope to michelle's family. >> i'm sure there's going to be people know aflac. aflac! but not when to use it. do i use aflac when the kids get slime in the plumbing? no. that's home owner's insurance. slime in my motorcycle. no. that's motorcycle insurance. slime everywhere? ughhh nooo, there's no insurance for that. do they help when i have bills health insurance doesn't cover?

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>> reporter: just months before michelle's death, there's her daughter alexis dancing happily in front of her proud mom. michelle's smile immortalized in this family home video. nearly eight years later after michelle is laid to rest, still one chapter remained open. jeremy's civil lawsuit against agent rusty rodgers, who reinvestigated the case with the florida department of law enforcement. jeremy alleged rodgers had violated his civil rights and tried to advance the theory that michelle's death was a homicide. >> about 100% of what agent rodgers and the fdle did on this case was essentially made up things so as to fit a theory. there was no probable cause, there never has been. >> reporter: but then, a railing. >> new tonight, a big development connected to the controversial death of michelle o'connell. >> reporter: a judge found that rodgers had probable cause to detain jeremy for homicide and dismissed the lawsuit in rodgers' favor.

the dismissal of the civil lawsuit has reinvigorated the o'connell family's quest for justice. >> our family can't rest, because it was so mishandled and all the science, all the evidence is there. i'm sure there's going to be somebody, if they see this, you know, program, they're going to say, "yeah, weeed someone to help us." >> i have a message for jeremy banks. you get to live your life, still a cop. michelle doesn't have a life anymore. if you think you're so innocent, then let us have our day in court. >> reporter: the family is also crusading for a law that would prevent departments from investigating one of their own ever again. jeremy's attorney says the case has profoundly impacted his client's life as well. what kind of toll has this taken on his life? >> it's absolutely ruined his life. his neighbors that walk up and down the street at 2:00 at night and will scream at him,

"murderer." >> reporter: but it's michelle's daughter alexis, who's lost the most. >> she would kiss her mommy's stone, and she'd say, you know, she wants to be a good girl, go to heaven to see her mom. you can't grieve until you get justice. you have to have your justice. >> interestingly, a local researcher who was looking into the case was found fatally shot earlier this year. >> was there a connection? police don't know. but they have ruled it a homicide, and an investigation is under way. we'll stay on it. i'm david muir. >> and i'm amy robach. from all of us at "20/20" and abc news, good night.

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