the other thing is the question of the time line. when you say wait for mueller, it's one thing if that's two weeks. it's another thing if it's four months or six months or a year. lisa green and ellie, thank you so much for joining us. >> it's shocking. you just kind of go into crisis mode. >> i don't think they knew exactly what had happened other than he was covered in blood. she was just broken and lost. >> there is a murderer out there. and it's terrifying. >> reporter: it was supposed to be an anniversary celebration. 32 years together! >> they were in love, even after all those years. they were very happy together. suddenly -- an intimate- moment turned to infinite terror!

>> i just hear help! someone's in trouble. i was scared. i was scared. >> reporter: a husband, found murdered in a closet! a wife, tied up in another. >> they found her on the ground with her hands behind her back. >> she just had bruising on her arms and on her face. >> inconsolable, screaming, crying. who could be behing this? >> it just eats me up inside! >> reporter: their only daughter, desperate for justice for her dad. be careful what you wish for. >> everybody gasped. nobody could believe it. >> this terrifies me because this could happen to anybody! >> reporter: i'm lester holt, and this is dateline.

here's dennis murphy with "unspeakable." >> reporter: the scented candles were lit. the jacuzzi jets turned on high. it was a belated anniversary evening, but not some big blow out. sandra and jaime really weren't that kind of couple. >> they were just always so kind to each other. and always very respectful. >> reporter: it was really the start of a life victory lap for the two. they'd raised a daughter, juggled all the usual things that families do, and now retirement for jaime was right around the corner. >> they sat there and they

talked about the future, and what they were looking forward to. >> reporter: but the future for these two would last no longer than the flame on that candle. by the next afternoon, there would be blood, lots of it. somehow, someone had turned a cozy celebration into a monstrous crime scene. >> it was just -- it was horrible. >> what in the world had happened in that house? >> i have no idea. >> reporter: the story of the two begins as high school meet-cute. sandra, the new girl from laredo assigned a seat in her houston classroom just in front of jaime melgar. their daughter lizz doesn't know how many times she heard that story. >> he used to pull on her hair. >> oh, you're kidding.

>> in the middle of class. >> "who's this guy behind me, pulling on my hair?" >> yeah. apparently, one time he invited her ice skating. and he told her a bunch of friends were going so it wouldn't really be a date. >> and when she shows up, there it's him and one of his friends.

and his friend left shortly after that. >> so a little bit of a scheme going on. >> yeah a little bit. but, you know, it ended well. >> reporter: and that was that. sandra and jaime were a done

deal, an inseparable couple. sandra studied nursing, and jaime set aside every dime he could for his family, juggling a job as a computer programmer while investing in real estate. >> happy family? >> very happy family. >> i was definitely a daddy's girl.

growing up. >> reporter: and jaime carried himself with a certain goofy joy, as his niece marissa campos remembers it. >> easy going guy? >> yes, very easy going. easy to talk to. had the worst jokes. >> they were so bad that you would just stop and groan. and they became known as jim jokes. >> reporter: marissa's aunt sandra would roll her eyes, then laugh indulgently at uncle jim. >> i remember her being like, "oh, your uncle. oh." >> reporter: the melgars' life revolved around not just family, but church, too. they'd joined the jehovah's witnesses early in their relationship, but by her early 20s, daughter lizz had left the church. newly independent, she rushed into a marriage. a bad one. >> true that he was involved in >> that was the end of it? >> that was it. i didn't want to live that kind of life. >> reporter: but her parents' marriage just kept going through sickness and health. in fact, in recent years, jaime was looking younger than ever on a vegetarian diet and exercise regimen. >> he realized he was getting older and he just wanted to make sure he was in the best physical shape. chemotherapy involved in that? >> at times, yeah. she also had epilepsy. >> did she have the seizures? did you ever see her -- >> yes. >> reporter: then december 2012 rolled around. their 32nd wedding anniversary.

sandra was ill on the actual day. so they went out together ten >> she was finally feeling well enough to go and have dinner. >> reporter: the next day, the 23rd, marissa's family would join them to celebrate again over a late lunch. ♪ turn up your swagger game with one a day gummies. one serving... ...once a day... ...with nutrients that support 6 vital functions... ...and one healthy you. that's the power of one a day.

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doorway, waiting for first responders, trying to calculate her family's terrible new math. >> i still didn't know

everything that was going on. >> reporter: in the bedroom: open drawers, a tossed wallet. had this been a home invasion? and where was her uncle jaime? then she glanced to her side,

and there, about 20 feet away from the bathroom, next to jaime and sandra's bed -- >> i just saw his -- his ankles. >> reporter: and this was what? in a closet area off the -- off the master, huh? >> he was in a closet.

>> reporter: so you just saw his feet. >> uh-huh. i w -- didn't even know what had happened to him. i just know he was -- his ankles were tied up.

it was horrible. >> reporter: there was jaime -- naked, covered in blood, on the floor, not far from his safe. a red rope encircled his chest, a phone cord looped around his ankles.

sandra, now freed of her ties, sprang from her closet captivity. a former nurse, she checked for his pulse and found none. your aunt was distraught.

she's crying. >> yes. yes. >> reporter: marissa, what in the world had happened in that house? >> i have no idea. i'm not sure who could have done something like that to him -- to them. >> reporter: first responders weren't exactly sure what they'd been dispatched to either. >> they told us that there's possibly two victims, and that's all we knew when we got there. >> reporter: emt stephanie robertson was the first responder on the scene. she checked on jaime. he was clearly dead, huh? >> yeah, clearly dead. yeah. >> reporter: you know, gunshot wounds from knife wounds. >> you couldn't really tell, there was so much dry blood. i did notice the gash down his neck. >> reporter: next, emt robertson found her way to sandra, by then collapsed on a chair in the bathroom, a family member by her side. >> she was kind of balled up a little bit. and she was crying hysterically. >> reporter: the emt started to assess sandra, who said her head hurt, but -- >> she said she has no injuries. >> reporter: still, sandra seemed disoriented. what time was it? that weren't true. i knew something was wrong... but i didn't say a word. during the course of their disease around 50% of people with parkinson's may experience hallucinations or delusions. but now, doctors are prescribing nuplazid. the only fda approved medicine... proven to significantly reduce hallucinations and delusions related to parkinson's.

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morning or afternoon? then, between gulping sobs, sandra said she simply could not remember what happened the night before. he wasn't going to be there to pick me up from the airport. >> reporter: a still very rocky sandra came, with family, to pick up her daughter. >> we both just broke down at

the sight of each other. >> she'd been through a terrible ordeal? you don't -- really know the whole story yet. but did you see injuries on her? >> she just had bruising on her arms and on her face. >> did she have a bump on her head? >> she did. she told me her head was hurting. and i could feel it back there. >> reporter: lizz insisted her mom get some rest. so the next day, when detectives came by the house where lizz and

sandra were staying, the daughter was the one to field their questions. >> and you flew in, uh, yesterday? >> yes. >> that's right. >> okay. >> reporter: and lizz, thought it prudent to record the

conversation. she updated the detectives on her mother's health. >> she's just in complete shock, and she has retrograde amnesia at the moment. she has a hard time remembering

things as it is because of the seizures. >> reporter: lizz had witnessed her mom's seizures before. and now she theorized that's what might have kept her alive during the home invasion. >> i think she, she probably had a seizure and that probably freaked out whoever was there, and maybe they thought they killed her. >> reporter: the detectives asked lizz to keep them updated on her recovery. and again, lizz says she urged detectives to look at her ex. he had a record of drug arrests. if not him, what about people in his circle? months dragged by without word on the investigation. >> you believe someone is out there, has gotten away with killing your father. >> yeah, absolutely. it was hard to sleep at night. i was --

every little noise was -- had me on edge. >> were you worried about your mother? >> oh yeah. >> that whoever this person was might come back for her? >> absolutely, i was constantly

worried. >> and how was her health at that time? >> she had started having seizures. and you know she was traumatized. she had post-traumatic stress, she had anxiety, she had depression. she was a mess. >> reporter: lizz clung to the hope that one of those leads she gave detectives would eventually pan out. but for now anyway it looked as though law enforcement was playing its cards close to the vest. according to prosecutor colleen barnett of the harris county district attorney's office, that was because they'd made some early observations about the crime scene. >> officers have investigated burglaries and robberies for many years before they get in homicide. and they thought that the scene looked kind of suspicious. >> so what was off kilter with this one? >> the fact that it didn't look burglarized. >> the drawers were open, i think, right? >> they were open a little bit, but nothing was tossed. >> reporter: but what about those items lizz noticed were missing from the house? and that backpack of apparent burglar's loot she found in the garage? well, detectives took careful note of many other items, pricey things that had been left untouched. and they theorized their suspect was someone already inside the house. house.

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>> reporter: the day before christmas eve, also the first anniversary of jaime melgar's death, was impossibly hard for his family -- >> i mean that's all we really think about. >> should be holiday season but it's that's awful memory coming -- >> yes.

>> back, huh? >> yes. yes -- >> reporter: the day a reminder too that jaime melgar's murder was still unsolved. >> so i imagine the family is waiting for an arrest to be made in this thing, huh? >> yes. we are anxiously waiting for that day to come. i mean doesn't matter if it's tomorrow or if it's ten years from now, but we -- we -- would

like some answers. >> reporter: but law enforcement wasn't exactly forthcoming with the melgar family. might have been a reason, they doubted jaime's murderer was a burglar, or even someone else in sandra and jaime's remote orbit.

>> there's always a first suspicion of family members, if there's nothing that really makes sense. >> reporter: and that suspicion had narrowed down to the person inside the house with jaime,

sandra. her account of a blacked-out 14 hours after their anniversary celebration. >> i wish i could recall. >> reporter: to investigators, was just too weird to be believed.

>> my memory is so bad. >> reporter: it seemed implausible to them that sandra really heard nothing the entire night. >> this is happening in a very small space? the husband is stabbed to death and found in one closet. and she's been tied up in another? >> that's right. >> reporter: the investigators closely studied that interview they'd conducted with sandra. they found her more indifferent than distraught. >> do you know what has happened today? >> my husband was murdered. >> how? >> i don't know. >> reporter: and when sandra broke down crying, the detectives couldn't recall seeing any tears -- detectives believed sandra's story morphed over time -- for instance the part about how long she'd waited to get out of the tub after jaime left to fetch the dogs -- at first she was vague -- >> and he just, you know, was taking a while so i got out. >> reporter: then more specific. >> about 15 minutes, 20 minutes. >> reporter: later another revision -- >> reporter: but, after almost two hours in, as investigators pushed her, sandra seemed to tweak this key element of her story -- >> actually i don't even remember hearing the dogs. my husband's the one that says he's got better hearing than i -- >> reporter: of course, the change-ups in sandra's story could be attributed to shock. but, as the detectives viewed it, sandra was being deliberately evasive. enhancing her story to align with a conjured-up crime scene. >> it sounds like a bloody event. was it? >> it was bloody in the area that he was in. >> reporter: to investigators' way of thinking, home invaders would have dragged at least a trace of blood on their way out

of the house. but crime scene techs did not find any. when the rest of the forensics came back, the findings had limitations. >> although you have the murder weapon, it's been washed in water for several hours. >> kitchen knife or something? >> a kitchen knife. a large kitchen knife. it was found in the bathtub. and so any dna that had -- could've been on it from the murderer was gone. it was washed away. >> reporter: what's more, no blood was detected on sandra. in fact, no dna or fingerprints linked sandra to jaime's body -- or jaime to sandra's. and while detectives had a hunch about sandra, the evidence didn't seem quite there yet for an indictment. as more time went by, it became clear to members of sandra's family, like her cousin diana, that law enforcement was eyeing her -- >> reporter: but as the investigation dragged into july of 2014, their worst fears were realized, lizz and her mom found out in a most unusual way. >> i went to the mailbox and it had been absolutely filled with fliers from lawyers trying to get our business for our pending case. >> and so i got onto the harris county website and i entered my mom's name. and i saw that she had been charged with my father's murder. >> so now you're in the full nightmare? >> yeah. >> reporter: a few days earlier, a grand jury had qui to indi >> quite frankly, i can smell bs from across the room. and when i sat down and spoke with her, her story was plausible, i didn't hear anything that -- rang -- kind of a false note. >> reporter: allison secrest -- mac's niece -- served as co-counsel. >> she's a sweet person, she doesn't have a temper. and it was really apparent to us she had a good relationship with her husband. >> reporter: they couldn't fathom how sandra was under suspicion for a crime that defied physical possibilities. actually hit in the head and was knocked unconscious. >> reporter: to these attorneys, the case seemed suspiciously thin -- >> "where's the beef? where's the crime?" i guess more importantly, "where's the investigation?" >> reporter: it had taken more than a year and a half to indict sandra. so what were the detectives doing all that time? a controversy is growing tonight over a document falsified by a harris county detective now working for the district attorney's office. detective carrizal got himself into serious trouble for falsifying a search warrant in a case not connected to sandra's. >> reporter: after the story broke, the detective left the

sheriff's department. would it end the case against sandra too? >> did your lawyers tell you, "this thing may never go to trial here. this thing has got so many holes in it?" >> that's what we believed. absolutely. >> reporter: by the summer of 2017, it had been three years since sandra's arrest. she had a right to a speedy trial. it was put up or shut up time for the da's office. >> when you read all your stuff and stepped back and you said, "what do i have here," what was the biggest problem?" >> the biggest problem was that i didn't have that many affirmative acts from her stand point. i had -- >> what do you mean there? >> i couldn't put the knife in her hand. i didn't have any eye-witnesses that she killed him. she didn't confess. >> what did you have going for you? what was the best thing you had going, colleen? >> her story was ridiculous. >> reporter: so the prosecution made the call, the people v. sandra melgar would proceed to trial. >> reporter: coming up, a deadly seduction? amanda-the prosecution thinks that sandra melgar lured jaime to the bedroom under the guise of sex play pros -- she's massaging his neck, and then she makes a strike straight up. but where was the proof?! >> this case outta scare the hell out of all of you when dateline continues. i switched to stimulant-free miralax for my constipation. stimulant laxatives forcefully stimulate the nerves in your colon. miralax is different. it works with the water

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>> reporter: august 2017. more than four-and-a-half years after jaime melgar was murdered in, what seemed at the time, a brutal home invasion. but now, sandra, his wife of 32-years, was on trial for

jaime's murder. she'd pleaded not guilty. it put daughter lizz in a painful, judicial paradox. >> the people versus are bringing you, the family, victim, justice in their mind. and yet, justice is putting your mother away. >> correct. i've lost my father and here i am, about to lose my mother. this is supposed to be s -- the justice system that -- it's just completely broken. >> reporter: prosecutor colleen barnett's message for the jury was simple, sandra -- and only sandra -- could have done this.

>> there's zero evidence. no evidence that anybody else did this. >> reporter: the prosecutor set out to dismantle the theory that jaime's death resulted from a botched robbery.

first responder, emt stephanie robertson, told the jury -- that to her -- the crime scene just looked off. >> it was a little -- disarrayed. the drawers were pulled out nothing was -- appeared to be missing. >> reporter: and the prosecutor used sandra's own words against her. the jury heard that interview with the defendant -- the one where detectives found her so oddly indifferent. >> do you know what has happened today? >> my husband was murdered. >> reporter: and sometimes her story to the detectives didn't gybe with what detectives believed to be the facts. >> she's just trying to tell a tale so that she can go on with her life without being in prison. >> reporter: for instance, her account of jaime getting out of the jacuzzi to quiet the barking dogs -- >> there was a next-door neighbor to the melgars who constantly complained about the barking dogs. she said that night, she didn't hear the dogs barking. like, she slept wonderful. >> reporter: of course, one of the main problems for sandra was the big picture, so you want us to believe, the prosecutor argued, that home invaders were slashing your husband to death just feet away from you and you remember nothing? really? >> nobody running? nobody saying anything? shouting? >> no. nothing. >> reporter: sandra's explanation was that she'd suffered from seizures and memory loss for years. reporter amanda orr was in the courtroom as the prosecution introduced some of sandra's medical history refuting that. >> she did go to her doctor's appointments, but reported that she was not having seizures. that her medication was controlling them pretty well. >> reporter: so if sandra was, in fact, lying about being unconscious for hours, then she had plenty of time to pull herself together and make the house appear ransacked.

>> she had a lifetime to get rid of the clothes, to wash herself up, to get ready for the -- the big finale. >> reporter: though not required to prove a motive, the prosecutor offered one up for the jury anyway. there was no evidence of infidelity or typical marriage troubles -- still she suggested that sandra wanted out. but their religion made it impossible to split up the usual way -- >> jehovah's witnesses don't allow you to divorce. unless someone's cheating, and it's very clear that jaime was not that guy. >> if i get divorced, i get ostracized and i can't talk with my friends. but if i kill him, and nobody finds out, i'm not ostracized. >> reporter: but wasn't sandra too frail to commit such a violent, close- quarters, crime? maybe not. the medical examiner's report concluded jaime suffered 31 sharp force wounds -- but none very deep. >> so kind of stab, stab,

taunting kind of injuries or how -- >> i don't -- >> how do you read it? >> or maybe not much force used. or maybe a weaker person. >> reporter: so how did the attack go down? the prosecutor had a vivid scenario of a lethal seduction. >> the prosecution thinks that sandra melgar -- lured jaime to the bedroom under the guise of sex play. >> so she gets jaime to sit down in the chair, and maybe she's massaging his neck, and then she pulls it out, and while he isn't looking, she makes a strike straight up all the way to his neck. >> reporter: it was a dramatic show and tell for sure. then, it was showtime for the defense -- the prosecution's case was all invented nonsense, they said. theory strong, evidence light. >> this case oughta scare the hell outta all of you. >> reporter: attorney mac secrest told the jury that sandra was the victim of bumbling, myopic investigation. >> now we've got jaime butchered, this lady falsely accused. >> reporter: and, the defense said, sandra was so clearly attacked herself, barricaded -- and bound. >> or so she's been tied up. she's been left in a closet for 14, 16, 17 hours. >> reporter: they showed these

photos in court, and told the jury sandra went to a doctor who confirmed her injuries. >> when sandy went to the doctor a couple of days later -- she had a full examination. and of course -- hematoma was found on her head. >> reporter: as for that interview. the defense said the only thing it revealed was that the blinkered detectives thought sandra was guilty from the get-go. >> would you want us to find the killer? >> of course. >> i don't think you do. >> reporter: and, they said it showed, in the most trying of circumstances, sandra remaining

consistent and composed. >> i had a seizure and so i usually can't move anyway. >> reporter: another point -- a forensic one -- the defense told the jury about dna evidence that had been collected but not presented by the prosecution. >> there's unknown male dna on various drawer pulls from the master bedroom, and door handles, and also on that backpack. so it's huge because it points to a possible other suspect -- >> reporter: and the csis had photographed a bloody swipe on the handle of the closet safe -- just a short distance from jaime's body. the defense told the jury how detectives never ran it for a possible print, nor had it swabbed for dna. >> isn't that the kind of evidence you'd wanna have available to consider?

why wouldn't you at least test it? >> reporter: the defense ticked off more examples of what they regarded as inept detective work, they never brought lizz's ex-husband in for questioning. ex-husband in for questioning.

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as seriously flawed. but perhaps their most persuasive argument was sandra herself. she didn't testify, but "houston chronicle" reporter brian rogers

said her muted appearance spoke volumes. >> you know there's an old adage in defense law. if you make your client look like a schoolmarm, do it. and she sorta comes across that way, as somebody -- >> reporter: kind of frail? >> small. and -- >> reporter: depending on a cane? >> yeah. you know, and you have a hard time believing she could even yell, you know, much less stab

anyone. >> reporter: and how could that same petite woman have managed, as the prosecution contended, to wedge a chair beneath the doorknob of the closet that she was already inside and beyond that, bind her own hands and feet. the prosecution had an answer for those houdini-like skills. >> she definitely prepared for this. i'm sure she practiced the chair behind the -- the door. >> reporter: the prosecutor said sandra had come up with an ingenious way to wedge that chair under the doorknob from the inside. by sliding a pillow sham along the floor. how's that, you ask? well, she played the jury this video of investigators

re-creating the process. >> the detectives videotaped themselves putting the chair on the pillow sham and pulling the pillow sham underneath the door so you can pull it closed from the inside. >> reporter: you have to be inside the closet, of course, right? >> that's right. >> reporter: prosecutor barnett said it wouldn't be all that hard for sandra to tie her own hands behind her back. she showed us what she showed the jury. >> reporter: so how do you tie yourself up with that figure eight now? >> it's pretty simple. all you do is just put it on your tie, turn it in the back and you just mess around with it any kind of way. the point is that it looks legitimate. not that it is legitimate. but it looks legitimate. >> reporter: the prosecutor argued sandra did this just minutes before the family discovered her, which explained what the emt said she did not see on sandra's wrists. >> she had no bruises, um, no ligature marks, nothing. >> reporter: but the very thought that sandra could have come up with these elaborate tricks and executed them. that's sheer speculation, said

the defense. >> that's a theory, folks. there's no evidence of that. >> reporter: a theory that the defense said investigators didn't even try to corroborate with the eyewitnesses who'd found sandra. daughter lizz said after that >> yeah they never reached out to anybody. they could have asked them about you know the theory of the chair her wrists so tightly bound. >> i have a big problem with them not following through and talkin' to witnesses who had personal knowledge. >> reporter: the prosecution said investigators followed the evidence and did a thorough job. it was now up to a harris county jury to decide sandra's fate. the first day of deliberations ended with no decision. >> reporter: when the jury's out, do you go back to your office and pretend to work or what? >> you can't work. no, you try and do other stuff, but you really can't. >> reporter: finally, on day two there was a verdict. family and friends filed into the courtroom. >> we were all, "everything's gonna be fine. this is a joke. no worries." >> reporter: surely the jury will see it the way we the family see it. >> exactly. >> reporter: sandra melgar stood to learn her fate. >> we the jury find the defendant sandra jean melgar guilty of murder as charged in the indictment. >> reporter: sandra collapsed into her chair, sobbing. lizz, beyond devastated, grasped for her mother as she was led away. >> it sucked the life out of me. i just felt the room spin. and i just felt like my world was collapsing. >> reporter: to prosecutor barnett, this was justice. both for the state and for jaime melgar. >> reporter: the jury sentenced sandra to 27-years in prison. her lawyers have begun the years-long appellate process. from behind bars, sandra wrote us this letter saying she's at peace because she knows she's innocent. her family supports her so she's not giving up. and lizz? well, she and her kids do their best to carry on without jaime or sandra. >> my daughter just loves her nana so much. and it was so heartbreaking. to tell her that nana wasn't coming home. >> reporter: when do you miss your dad the most? >> every day when i look at my kids. because i know what a wonderful grandfather he would've been.

the jokes and the games and probably the toys he would've made for them. >> reporter: they never got a chance to roll their eyes at a jim joke, huh? >> yeah. >> reporter: that's all for this edition of dateline.