carolina is coming to an end, but don't take off just yet. stick around for "20/20," which starts right now. that's fine. >> tonight on "20/20" -- >> i grabbed my gun and i just put it in the air. >> one has passed a i way. >> it's no way to start the school year. a s.w.a.t. team searching dorms when a drunken party turns into chaos and killing. >> you saw people on the ground? >> yes. >> can i call my mom? >> no random shooter, but this boy, a fellow student. >> i immediately knew this was a big story. >> their 20-year-old son, dead.

>> everything stops around you. everything. >> so you're in the second floor of the building. >> tonight, recordings in real time from the crime scene. >> unprovoked, hit in the face. >> from the interrogation room. to the courtroom. >> he was bullied, threatened, and attacked. >> with that gun in his hand, he was the most deadly person in sight. >> but was it self defense, or retaliation. >> you have been portrayed as a bunch of bullies. everybody was hammered. >> what will the jury decide? >> what would you do? >> a chance encounter. >> good evening. i'm elizabeth vargas. david is away on assignment. when you were shopping around for colleges, you maybe thought about the school's academics, athletics, maybe even alcohol policy.

but you probably didn't think about whether or not guns are allowed on campus. tonight, one family says they wish they had, because it resulted in death, and a murder trial, with a new one scheduled for next month. here's matt gutman. >> reporter: its motto is, "the world looks different from here." and it does. northern arizona university sits 7,000 feet in the air. surrounded by the snow-capped san francisco peaks and a ponderosa pine forest here in flagstaff, arizona. plenty of wide open spaces, for any kid looking to strike out on his own. >> there's so much to do. you have sedona and the grand canyon. the mountains. >> flagstaff is really homey if you will. it's got a comfortable, welcoming feel to it. nau, same thing. i mean, flagstaff and nau, they're not separate. it's just all one big community.

>> nau is one of three state schools in arizona. it's got about 20,000 students, but it has a very close-knit feel among the students on campus. >> reporter: one of those students who arrives as a freshman in the fall of 2013 is 18-year-old colin brough. here to study business. and how did he come to choose nau? >> he applied to csu, boulder and nau. and nau was the furthest away so that's why he picked that one. because he wanted to be away from home, and just wanted to be on his own. independent. >> reporter: claudia and doug drop him off, 10 1/2 hours away from their colorado home. sure he will be safe. >> looking around this campus, can you tell why he liked it so much? >> well it's a great community. it's a beautiful community. >> reporter: at first, it seems colin is suffering from the all-too familiar fall freshman blues. >> he would always kid me, "i'm not going to be homesick. i can't wait to go."

two months later, "i think i made a mistake. i want to come home." >> reporter: but the jitters start to fade once colin begins making friends. like fellow freshman nick piring. >> we became random roommates freshman year in the dorms. i met his family the first day, just became really close right off the bat. >> reporter: would you say he's your best friend? >> one of my best friends, for sure. we ended up rushing the fraternity second semester. >> reporter: kyle zientek also meets colin at that fraternity. well, you're smiling, you're grinning, so. >> just thinking about just the kid's like heart, honestly. the smirk that he always had too just was, i don't know. that kid had something just about him. >> reporter: the boys join the delta chi fraternity at nau. a school where greek life is big on campus. the people, the programs and of course the parties. parties like this one, shot by an nau student. that's the part that worries colin's parents. what was your impression?

>> i kept thinking, like "animal house." ♪ 'cause that's all i really knew. >> reporter: that paints a picture. >> i wasn't happy about it. but i told him he could make those decisions. >> reporter: and that was your whole philosophy bringing up the kids, right? when you're in my house i'm going to take care of you, you're going to be safe, but when you go off to college. you're going to explore, make choices that you're going to live by. >> reporter: by sophomore year colin and his friend nick move off-campus to this apartment complex known as "the courtyard." it's a popular spot for delta chi, housing several of their fraternity brothers and is conveniently located just across the street from nau. >> we had the whole little courtyard so we could go out there, maybe, you know, just get together, play some beer games or something. >> it had sort of a reputation at the time for being a place to party and hang out.

>> police were often visiting the courtyard, getting noise complaints, getting complaints of students drinking. >> reporter: were you concerned that colin would go off to college and start just partying his face off? >> i was always concerned about that and of course i didn't like it. but i knew in the end he would get it out. >> reporter: but before he would get the opportunity to do that, tragedy strikes on campus. >> nau has been in existence for 118 years, and for 116 of those years there had never been a shooting on campus. that changed on the night of october 9th, 2015. >> reporter: the night starts out like so many others, with a party at the courtyard. what are you guys doing that night? >> we're just hanging out. just a couple people drinking, it's thursday night. it wasn't anything crazy. >> reporter: do you guys even

know what started everything? >> no, no, i don't know what happened and how it started. >> reporter: around 1:00 a.m. nick and kyle along with several other people at the party say they hear what sounds like an argument going on in front of the courtyard. >> it wasn't a memorable night. >> reporter: zach volpo and nick pletke are also delta chi brothers who are at the party that night. >> there's a verbal confrontation going on on the street. >> all of the sudden i see the group move into the parking lot, and then that's when i saw the flashlight flick on. >> reporter: do you remember ever seeing the gun? >> i remember seeing a light. i thought it was, security guard or a cop or something. had no idea. >> i look down for a second, either at and all of the sudden i hear three, four loud, really, really loud bangs. i thought it was fireworks or something. >> reporter: zach runs across the street into the nau parking lot and he's horrified. colin brough and nick piring are down. both of them bleeding on the ground. each of them shot twice. >> i was in so much shock, i had no idea.

and so i saw a puddle of blood next to me. >> the only person i didn't recognize was the one standing, and i realized that he was the gunman. immediately turned around, book it back, try to find some cover. >> i saw this blinding light, it kind of clicked with me that something's not right. >> reporter: the shooter fires off several more rounds. this time hitting delta chi brother nick prato and kyle zientek. how do you get shot in the back? >> i turned around when i saw that light. next thing i know, like, on the ground and it's just, it's like all numb. >> reporter: when we come back, how did a college party turn into a war zone? as police arrive, they confront the teenage shooter. body cameras capturing all the action. >> can i call my mom? >> reporter: and you'll be shocked when you learn who that shooter is. shooter is. stay with us. with 33 individual vertebrae

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there's a guy outside and he's shooting people. >> one male, actively shooting. >> people down. >> i didn't know what was going on. i realized i was bleeding out on the floor. >> reporter: had you ever seen a gun on campus? >> no i have never seen a gun on campus until that night. >> reporter: are there any smells or sounds that you remember? >> screaming, there was a lot of commotion.

>> reporter: in the first blast of gunfire, junior colin brough is shot in the chest and in the shoulder. and nick piring is shot in the shoulder and the hip. >> i could see colin from where i was, and i was yelling 911, like, someone call 911. >> the parking lot where the shooting took place, there's a dormitory that overlooks it, and a lot of people had their windows open, so they could hear what was happening. >> reporter: so you are second floor up, second window in right there? >> yes. >> reporter: okay, i mean that's as close as you can get. that's within spitting distance. >> the gunshots were pretty apparent. >> reporter: miqui scollard, a sophomore at nau, jumps from her bed and runs down to the parking lot into a crowd she doesn't know with bullets still flying. you begin to see people on the ground here. >> yes, and the first person i see is nick.

he's laying here and i'm like, where are you hit? like where are you hurting and he's like my shoulder. i see his shirt, and he's got a pretty big bullet wound there so i put my left arm, my left palm on his shoulder. >> reporter: what miqui doesn't realize is that at this moment the shooter is still on the scene, right behind her. >> and before you know it there was more gunshots. >> reporter: so you literally administering first-aid to somebody who had been shot? >> yes. >> reporter: and then you heard gunshots behind you? >> and i hear gunshots again and i said, he's still shooting. don't move, don't scream. >> reporter: that's when the two fraternity brothers nick prato and kyle zientek were hit. >> afterwards i remember looking to my left and the boys that i now know from the shooting were screaming, stop shooting! stop shooting! i remember one saying, he dropped the gun. he dropped the gun. before you knew it, we had officers on all of us with guns in our faces. >> code three. >> reporter: nau police begin arriving with body cameras rolling. every second of the aftermath is caught on tape. >> check that kid back there.

>> multiple victims. i am going to need three or four ambulances at least. >> reporter: this video shows the chaos still unfolding, the young boys bleeding, lying shot on the ground. miqui scollard applying pressure to nick piring's wounds. and on the other side right there, a quick glimpse of frantic 18 year-old on the ground, but this one is being handcuffed. >> turn around, on the ground, on the ground. >> please go help them officer, please. please. please go help them, i'm so sorry, please. please go help them. help me. i'm so scared. >> i have one detained. he identified himself as the shooter. >> reporter: the hysterical student on that body cam is nau freshman steven jones. he had only been on campus a few weeks.

>> i'm so scared. i want my mom. >> is your name steven? >> yes, sir. >> have a seat. >> it's just a very, very raw moment which obviously he probably doesn't know he's being recorded. >> i have the suspect in the back of my car right there. you identified yourself to me as the only, as the shooter. >> there's nobody else involved? >> no, nobody but me. i take all responsibility. >> okay. >> reporter: officers begin securing the scene, searching through the nearby dorm, outside paramedics work to save the four badly injured college students. >> i was just looking up in, into the sky. just screaming at the sky. >> reporter: what were you able to see? >> i could just see colin like in the rocks at that point and just unconscious. i remember yelling at the paramedics to go help him.

i guess there was nothing they could do for him. >> reporter: 20-year-old colin brough lay dead on the ground. while his three fraternity brothers are raced to the hospital with multiple gunshot wounds. but in the back of that squad car the suspect steven jones isn't acting like a deranged rampage shooter, more like a distraught kid. >> oh, my god. >> reporter: repeatedly begging for his mom. >> i'm so scared. can i call my mom? >> we'll call your mom for you. we just got to figure all this stuff out first. stand by real quick. >> reporter: 500 miles away in colorado, another mother and father are about to get devastating news. >> we really never talk about that day together. >> reporter: even to each other?

>> mm-mm. >> our youngest, doug, came down and he had gotten a text that there's a shooting at nau. first thing i did was text him. >> reporter: what time is this? >> 6:23 in the morning. >> reporter: you remember the exact time of day. >> yeah. i called the flagstaff police, and they said the nau police were handling it. so i got to the nau person that was handling it and she told me colin had passed. >> it was just like a bad dream and i kept thinking, this isn't real. like, this isn't -- this can't be. >> reporter: and then what's your next move? do you try to fly right away to flagstaff? >> you don't move. you -- >> yeah. >> you don't move. everything stops around you.

everything. >> reporter: while claudia and doug brough descend into a paralysis of pain, the community of flagstaff is reeling, trying to understand how this could happen here and why. did you know at the time, that night, that it was a student? >> no. >> reporter: that had done the shooting? >> i had no idea. >> reporter: but it is a student, and when he's led into a police interrogation room cameras continue to roll. the college freshman, with blood on his hands, literally. but was the terrified teenage gunman actually fighting for his own life? the story he tells police, and the blurred lines between murder and self-defense, up next. it's all that stuff. in a house that you own. because homeownership?

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campus. >> this is not going to be a normal day at nau. >> all the victims involved are nau college students. >> i immediately knew this was a big story. this wasn't your traditional school shooting. this was different. >> reporter: the shooter is 18-year-old steven jones. he identified himself to police at the scene. >> he had only been on campus about three weeks. school had just started. >> he'd grown up in a middle class family, suburb of phoenix, homeschooled by his mother, was having some trouble apparently adjusting to college but was just beginning to make some friends. >> just have a seat over there in that chair. >> reporter: the distraught teenager is led into a tiny interrogation room, still handcuffed. >> can you put my hair out of my face, please? >> reporter: shaken. and when he's finally able to see the blood on his hands, horror at what they have

allegedly done. >> put your hands together like this. there we go. perfect. >> tight. >> what happened tonight? >> i don't think i should answer that without calling my dad first. >> reporter: at first reluctant, steven begins to describe a night that started out pretty tamely. he and some friends at another student's place off campus. there were girls and the video game "guitar hero." >> did you guys imbibe on any alcoholic beverages? >> the girls were. they had beers. i had a sip of my friend's beer but i knew that i was driving and i couldn't afford to. >> reporter: jones says after about a half an hour, he and three of his freshmen buddies jacob, shay, and hunter, want to head back to campus. they start walking towards jones' red mustang parked in that lot across the street from the courtyard, where that frat party by now is in full swing.

but along the way, jones says, they lose track of their friend hunter. so the three freshmen are walking down here. i went back to the scene with retired dallas police chief and abc news consultant david brown. they lost a friend, and they go knocking on that door. >> it seems pretty innocent to me. >> 10 or 12 dudes came out. and they started like, like talking [ bleep ], get the [ bleep ] off our porch, and then we were, we just decided to turn around and walk away. >> reporter: there's one person who seems to be the lead aggressor, at least verbally. >> colin bough, is what witnesses are saying, is kind of the leader of the pack. >> what were they saying? >> going to kill you, you [ bleep ], like, i bet you couldn't fight, go back to the freshman dorms. they were obviously very drunk. >> reporter: toxicology reports will later prove that colin brough was in fact very drunk. more than three times the legal limit, and he also tested positive for marijuana and

for xanax. these guys are retreating. they're backing up. and it gets uglier and uglier. until somewhere around here, this is where everything changes. >> right. steven jones gets cold-cocked, unprovoked, hit in the face. >> he just [ bleep ] rocked my world, like, i have no idea what was going on, my glasses fell off. i could barely see. >> reporter: now, it's not clear who did throw that punch, but eyewitnesses all later confirm that it was not colin brough. >> a reasonable person might think, "yes, i might be seriously injured now. and so now, i'm taking off, running toward my car, trying to get away." >> reporter: and that's exactly what he does. jones tells police that as he retreats towards his red mustang, he is pursued, chased into the parking lot. police ask him to draw a map of his movements. >> when i started running from here they were right behind me. i thought i was going to die. >> now, your perceptions may be

off-kilter because you've just been cold- cocked. maybe you think people are closer than they are. maybe you're hearing noises louder than they really are. it can be that extreme when you're in fight or flight mode. >> reporter: although he is able to get the doors unlocked, steven says in his panic he can't find his other key to put in the car's ignition. and that's the moment, jones says, when he opens the glove compartment, pulls out his glock .22 handgun and gets out of the car. >> i turned on the flashlight and pointed it at them and said i have a gun, don't [ bleep ] move. and then -- >> where were those two guys at that time? >> i was right here in front of my car and they said i'm going to [ bleep ] kill you and two of them ran at me as fast as they could. >> reporter: those two guys would turn out to be colin brough and nick piring. jones says he was standing two or three feet in front of his car when he pulled the trigger. >> he was running at me. he was staring right at me. he was saying he was going to kill me.

i was afraid for my life. >> reporter: jones says after shooting colin and nick, the rest of the frat guys in the parking lot descend on him, pummeling him on the ground. >> so i grabbed my gun. i just put it in the air. i wasn't trying to hurt anybody. i wasn't even aiming at anybody. >> how many rounds did you fire? >> i don't know. i just remembered my training, my dad training me. >> reporter: he tells police his father, an nra certified instructor, taught him to shoot at an early age. >> i was trained to fire until it's not necessary to anymore. >> reporter: and these photos from his social media accounts certainly paint the picture of a boy and his guns. but as it turns out, steven jones was not breaking the law by having that gun locked in his car on campus. >> the state universities don't permit guns on campus, with the exception of state law allows you to keep a gun in your car as long as it's not visible and it's locked up.

>> reporter: it is a detail that colin's dad doug just can't get past. >> if there wasn't a gun on campus, period, we aren't sitting here. colin's sitting here. >> that's what we have to change. all learning institutions should be weapon free. >> reporter: back in that interrogation room, after more than two hours of questioning, at 4:40 in the morning, officers break the news to jones about what happened to the boys he shot. >> three people in the hospital. one has passed away. >> i was just trying to walk home. >> reporter: his self-defense story notwithstanding, officers photograph jones' injuries. his clothes are collected, and in a white disposable jumpsuit, the freshman who had been on campus less than a month is led

off to jail, charged with first degree murder. as a college campus mourns one of its own and a family prepares to bury a son, another one is preparing to mount a defense. coming up, the trial of steven jones. the college students he shot squaring off against him. >> so many young people testifying one after the other. >> reporter: why don't prosecutors believe his story of self-defense? >> as compelling as he is in this interrogation tape, talking about how scared he was, and why he did what he did, the authorities clearly believe they know something more. ♪ i'm like a sponge for this stuf i can learn it. get it. sell it. i can do this job in my sleep better than some people can do awake. i just want to make sure this brain stays in hyperdrive.

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>> reporter: the evidence in the steven jones case, crime scene photos, bullet casings, that nine-millimeter glock .22 with its attachable flashlight. so that's what it would look like. all pieces of a puzzle that prosecutors hope will convince a jury that steven jones was not in fear for his life when he fired his gun but is in fact guilty of first degree murder. >> pleaded not guilty. >> reporter: what is indisputable is that jones' actions that night left one boy dead and three others with injuries, both physical and emotional. >> i mean, we've talked about it and we've shared feelings and stuff but we don't talk about that night in particular. it's just, it's not something we

really want to keep on the forefront of our minds. >> reporter: but at trial, they will be forced confront what happened that night. in their opening statements prosecutors and defense attorneys paint dramatically different pictures of what happened in that nau parking lot. >> to the victims, the defendant was an assassin emerging from the darkness and they had no chance to protect themselves before the defendant unloaded ten rounds form his gun. >> reporter: prosecutor ammon barker argues steven jones was a calculating, cold-blooded killer. >> the question for you during this trial will be what was the defendant's intent when he shot these four unarmed victims. >> reporter: it is a question the defense is eager to answer in its opening statement. >> this is a case about an 18-year-old kid who found himself in a situation where he was surrounded, bullied, threatened and attacked and did what he had to do to protect

himself. >> reporter: when the testimony begins it does little to clarify what actually happened that night or even how it all started. >> people had vastly different stories of what they remembered or they saw or how many people were involved. >> reporter: and remember, some of those people were impaired that night making memories murky. >> describe how many people you think you saw out there. >> i want to say i saw about four or five. >> probably around eight people. >> do you recall how many shots? >> maybe two. >> i believe it was three to four. >> reporter: and this theme of contradicting accounts will be a recurring one throughout the entire trial. take the testimony of jakob mike, one of the two freshman friends who was with steven jones that night. >> i saw people fall on the ground and then the light panned over me, i guess, and i put my hands up and i was like, it's

me, it's me, jacob. >> what were you thinking? >> i was scared. >> of who? >> steven. >> reporter: he says he never thought his life was being threatened by those drunken fraternity boys. but on cross-examination, defense attorneys remind him of a 911 call he made where he sounds terrified. >> 911. >> this guy's killing my friend. >> where are you? >> mountain view. >> what's going on there? >> someone is [ bleep ] attacking my friend. >> i was just hysterics and out of, out of my mind, i guess. >> reporter: then there are the three surviving victims. nick piring testifies first, saying he never heard his friend colin threaten steven jones or saw him lunge at him. he also tells jurors that he witnessed colin get gunned down and it was only at that point that he ran towards him. but there's a problem with nick's testimony, and the defense zeroes in. >> you told police a pretty different story that night, didn't you? >> what did i tell them?

>> you told them that you ran up because you were trying to calm people down. >> correct. >> in fact, you told the police that you were, to use your words, mainly trying to calm colin down. isn't that what you said? >> that is correct. >> reporter: next on the stand is nick prato. he was shot in the neck during that second wave of gunfire and testifies he witnessed both colin and nick piring also get shot. >> right after i watched colin get shot, nick piring jumped in the air and that's when i saw nick piring, midair, get hit.>> lawyers score another point, highlighting an inconsistency from his original police interview. they read back his own words, where he never mentions seeing anyone get shot. >> well let's take a look. "it was hard it was hard to make out. once i heard the gunshots of course i was looking over there to see what the hell happened."

you didn't say anything about him getting shot, did you? >> no, i did not. >> the defense is trying to do two things here. number one, highlight inconsistencies in these fraternity brothers' stories. number two, try and make their actions, their movements seem as menacing as possible. >> reporter: and that brings us to kyle zientek, the last of the gunshot victims to take the stand. he tells jurors he was shot twice while running away from steven jones. but the defense has the goods yet again. listen to what he told police. >> you were asked, "so, in other words, were you running towards the shooter or away from the shooter?" >> yes. >> could you please read your response to the jury. >> i think i was running towards the shooter to get his gun. >> reporter: three key witnesses tripped up on cross-examination. but the most dramatic moment of the trial is still ahead. when we come back, what you almost never see. the defendant steven jones takes the stand in his own defense.

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the nau student who opened fire on other students, taking the stand. >> reporter: on day seven, steven jones may be feeling either lucky or desperate. because he's about to do something rarely seen at a first degree murder trial. >> your honor, the defense calls steven jones. >> reporter: take the stand in his own defense. >> when steven jones was called to the witness stand, it was incredibly quiet in court. you could hear a pin drop. >> hello, my name is steven jones. >> reporter: jones begins by recounting for the jury about that scuffle in the street that turned deadly. >> they were screaming and yelling and stuff and the next thing i know i just got punched. it just rocked my world.

>> what's the very next thing you remember? >> as i was getting back up i felt someone behind me try to grab the back of my shirt and i started running. they were saying things like, "get the [ bleep ] back here. what the [ bleep ] are you afraid of?" >> reporter: he says he gets to his car and makes that split second decision to grab his gun and get back out. >> they were running as fast as they could full force, looking me dead in the eye. >> and then what's the very next thing that you remember? >> i fired my gun. i knew that if i waited even another split second i would get seriously hurt or die. >> reporter: the parents of the boy who did die are apoplectic in the courtroom. >> it was hard. it was hard for me to even be in that room and you could just see how cold and just almost removed he was.

>> kind of like a video game. >> reporter: but did any part of you think, "man, he's also a kid. he's 18 years old. he's a child." >> oh. i said that. i said his life was ruined as well. >> reporter: and jones' story on the stand isn't holding water for some others who are in court listening, namely, his victims. nobody deserved to die that night, period. but would you say that colin was the aggressor? >> no, i wouldn't say that. i wouldn't even say it was an aggressive situation. it was a verbal argument from what i could see. >> reporter: there are people who say that steven jones was just defending himself against a bunch of bullying frat guys. >> that's his defense. i never even saw the kid until he came back with a gun, so -- >> reporter: and when it's the prosecution's turn to cross-examine steven jones they hammer him on that critical question of intent. >> okay, but you were going to kill someone because you thought you were going to be killed.

correct? >> no, it was never my goal to kill someone. >> what do you think happens when you shoot someone in the chest? >> they get seriously hurt. >> that's what you think happens every time? >> sometimes people who get shot in the chest die. >> right. >> reporter: and then taking a page right out of the defense attorney's playbook, they press him on exactly where he was when he fired his gun, returning to this police interview. >> got out of the car and stood in front of my car maybe like two, three feet, like right in front of the door. >> reporter: two or three feet he says, but the evidence shows that after getting out of his car he actually walks over 90 feet toward colin brough, before he says colin charged him. back in that parking lot i saw for myself just how far steven jones actually traveled from his car. >> it was over 90 feet between him and the next closest person. >> reporter: big difference between a couple of steps and 90 feet. >> this is a lot of distance

between where he was feeling pressure. >> reporter: right, it's seconds. >> and where the next person was that would've been on top of him. >> reporter: even if you're running that, that takes some time. >> the authorities clearly believe that he went those 90 feet in order to exact revenge, to kill someone, not, they believe, just to defend himself. >> i didn't know how far away they were at the time. >> okay, but you keep saying to the officers that you were right in front of your car, right? >> correct. >> i mean, you say that again and again. so each time you're describing that you're just wrong about it, right? correct. >> putting a defendant on the stand is always a risk. when he has to admit an error on an important issue, that's a real danger for the defense.

>> reporter: before steven jones leaves the stand, his own attorneys are hoping to leave the jury with one lingering exchange. >> steven, if you didn't fire your gun, do you think you would be sitting here today? >> no. >> reporter: day eight. closing arguments. the defense implores jurors to put themselves in jones' shoes. >> if you're being tackled by a group of guys like this, drunk, outnumbered you, they're clearly trying to get your gun. you don't have much more time before they're going to overpower you. what would you do? >> reporter: and they remind the jury that under arizona law steven is justified in using deadly force if it is to protect himself from being seriously injured or killed. but prosecutor ammon barker tells jurors jones' story is riddled with lies for one reason. because he is trying to bolster a bogus self-defense claim. >> we know he was punched in the face. but what he did afterwards has nothing to do with self-defense and everything to do with retaliation. >> reporter: jurors head out to

begin deliberations. and as the hours, then days pass, five families are left to wait and to worry. i know you're not in the mindframe of blaming -- >> the parents. i blame the parents. i blame the parents. he was a young kid. he was taught to shoot silhouettes. not even, like, tin cans like you would think if you're teaching a kid. but this was the way he was raised. and he did what he was trained to do. >> reporter: when we come back, the jury deciding the fate of steven jones has a stunning message for the judge. >> mr. foreperson. >> reporter: and for us, too. >> i was juror number two in the steven jones trial.

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including tuberculosis. serious, sometimes fatal infections and cancers, including lymphoma, have happened; as have blood, liver, and nervous system problems, serious allergic reactions, and new or worsening heart failure. before treatment, get tested for tb. tell your doctor if you've been to areas where certain fungal infections are common, and if you've had tb, hepatitis b, are prone to infections, or have flu-like symptoms or sores. don't start humira if you have an infection. ready for a new chapter? talk to your rheumatologist about humira. this is humira at work. >> reporter: it was supposed to be judgment day for 20-year-old steven jones, facing life in prison if convicted of first degree murder. but after five days of deliberations, the jury of six men and six women file back in with a shock for the court. >> the jury has indicated that

you do not feel that additional deliberation or assistance will help you in reaching a verdict. is this correct? >> reporter: the jury is hopelessly deadlocked. >> this court is therefore going to declare a mistrial in this case. >> they tried but just couldn't agree. >> reporter: it is an inconceivable blow to claudia and doug brough. >> disbelief. really just disbelief. like, how could they hear all the evidence and not come back with a guilty verdict? >> the key issue was, did the state prove beyond a reasonable doubt that steven jones committed a crime? >> juror robert nagle spoke only to "20/20" after the mistrial. >> in my opinion, the state did not prove their case. >> reporter: when the jury first voted, most believed steven jones was guilty of a crime. they just couldn't agree on what crime. >> some thought first degree murder, some thought second degree murder, some weren't sure. >> reporter: but nagel says he

and several of his fellow jurors actually found steven jones to be a more credible witness on the stand than the fraternity brothers. >> i believe once that colin brough and nick piring came toward steven jones, he had the right to protect himself. >> reporter: and for that, he says, he believes jones was justified in using deadly force. >> steven jones had absolutely no choice but to shoot colin brough. when i asked the question, "hey, who would've shot these boys in this situation?" four of us said we would. >> reporter: by the end of deliberations he says the jury was evenly split. prosecutors intend to try steven jones again, hoping they'll have better luck with a new jury. but the young men who survived that night are ready to move on. >> a lot of us want to forget about it. i mean obviously not forget about colin and all that, but we kind of want to forget about, i don't know, just move past it. i guess should say.

>> reporter: have you prepared yourselves for the possibility that steven jones -- >> we're not going there yet. no. >> reporter: -- may walk free? >> no. i do not believe that in my heart for one minute. no. i believe that justice will prevail so this doesn't happen to anyone else. >> that retrial she wants is now scheduled to start in october. we contacted steven jones and his family, but they declined to speak in advance of the trial. thank you for watching. that's our program. for david and all of us here at "20/20," have a good night and a great weekend. >> coming up on "action news," an updated track as hurricane

irma aims for florida. a helicopter crash claims half of the popular country duo. next. ♪ ♪ "action news," delaware valley's leading news program with jim gardner. ♪ ♪ >> this is as real as it gets. nowhere in the florida keys will be safe. there is still time to evacuate. those words from the national weather service to people in