over my body. >> and it ends up costing you. deadly fruit. fresh summer cantaloupe. it seemed healthy. but it caused one of the deadliest food outbreaks in u.s. history. >> if any one of those things would have been prevented, this tragedy probably wouldn't have occurred. >> how it could have been prevented and could still happen again. revealing investigations. fascinating characters. stories with impact. this is "cnn presents" with tonight's host, randi kaye. it is one of the worst atrocities to emerge from the war in afghanistan. in a chilling shooting rampage sergeant robert bales allegedly shot down 17 civilians. his lawyer says he may have had post-traumatic stress disorder. a diagnosis that could be used in his defense. that is a scene playing out more and more in courtrooms around the country. vets charged with violent crimes are saying ptsd made them do it. and juries are having to decide, should ptsd be a defense for murder? chris lawrence investigates. >> reporter: raymond williams had worked his whole life for this moment. just retired. looking forward to traveling with his wife and seeing the grandkids. but he went out to get his mail one spring day and was gunned down by a man he never met. his wife found the body. >> she said, "matt. matt. somebody shot dad." and "shot dad." it didn't register. i'm thinking where is he now? did they take him to the -- what hospital is he in? and before i could even get another word out, she goes, "he's dead." >> reporter: raymond's killer was a husband, father and veteran soldier just out of the army. nick horner earned the combat action badge for fighting in iraq. now he was facing the death penalty for his crimes. >> not in a million years could i have believed this was true. because nick would never -- he could never hurt anyone. nick pulled the trigger, but that wasn't nick. >> reporter: this isn't a whodunit. it's a why-dun-it. one minute an ex-soldier is out shopping with his wife. the next he's murdering two people and shooting a third. defense attorney tom dickey says horner's not to blame. >> i argued to the jury in my opening, i said i believe that the iraqi war came home that day. >> reporter: of the troops who fought in iraq or afghanistan, the military has diagnosed 90,000 with post-traumatic stress disorder. the veterans administration, well over 200,000 troops. after a decade of combat, ptsd is now showing up in the courtroom as a criminal defense. but is it a get out of jail free card? altoona is a small working-class town in central pennsylvania. horner's bloody rampage was the only murder case in 2009. that april morning, nick horner dropped his kids at school and went shopping with his wife. they argued. and nick stormed off, armed with his .45-caliber handgun. >> he left walmart and went to a bowling alley where he sat all afternoon and drank several -- well, at least two pitchers of beer. >> reporter: prosecutor jackie bernard says horner was relaxed and signed up for several bowling leagues. and then he walked to a nearby subway, intending to rob it. witnesses say horner was pounding on the back door, trying to get in. but this wasn't your typical robbery because evidence shows that horner cut the electrical wires to the restaurant and even tried to shoot out the utility box. horner's lawyer thinks he was in the middle of a ptsd episode. >> why do you do that? why do you in broad daylight enter from a rear and announce yourself by firing, you know, five or six shots all over the place into the back of the building? >> reporter: inside, horner shot and killed subway worker scott garlick, a teenager about to graduate high school. then he threatened and shot another worker, michelle petty, and stole about $100. >> when he left, he walked over scott's body as he lay bleeding there and said to him, "sorry, didn't want to have to do that to you." >> reporter: several blocks away, horner spotted raymond williams. prosecutors argue he killed williams for his car keys to try and get away. when horner was charged, he pled diminished capacity, wanting to convince a jury he was not guilty because of ptsd. so the robbery weighs against him. and the fact horner had time to think about the first two people he shot before walking away and killing raymond williams. but this was a man with no real history of violence. except for what he experienced in iraq just a few months earlier. so what would the jury weigh more? the ptsd defense for murder was successful in 2009 when an oregon jury found jesse bratcher guilty but insane. instead of serving 25 years in a maximum security prison, the iraq war veteran is being treated at this mental hospital. he's allowed to take supervised hiking trips and could be released this month. >> i can honestly tell you that i would have never shot anybody if it hadn't been for ptsd. >> reporter: the ex-soldier got into a shoving match with a man who he believed had raped his girlfriend. >> i remember him threatening and pushing me. then having flashbacks of iraq, like seeing my buddy get killed in iraq. >> reporter: bratcher unloaded six hollow-point bullets into the victim. reminiscent of the rockets and mortars he encountered in iraq. >> after i got back i had anxiety so bad, i thought i was going out of my mind. >> reporter: iraq and afghanistan veterans with ptsd have been acquitted of lesser crimes like robbery. some have had prison terms reduced. but bratcher's attorney says his is the first major criminal exoneration linked to ptsd. >> it's not a defense that has been written up a lot. it hasn't been used a lot. >> reporter: but that's changing. now defense attorneys are advertising their expertise to troops facing charges. one veterans group is even publishing a manual with tips like finding witnesses from the defendant's squad. >> someone who can testify as to the horrific events that the defendant has gone through. because they're -- those are the things that sell to a jury. >> reporter: nick horner's mother says after iraq her talkative son didn't mumble more than a few words. so the family noticed something's different? >> his wife said that she would find him in the basement crying in the corner. he just wasn't my little boy anymore. >> reporter: horner's lawyer argued he was confused by a mix of prescription drugs used to treat ptsd. >> that's what i've been trying to argue throughout, is that nick is sick. and not evil. >> reporter: the prosecutor told jurors those drugs did not impair horner's judgment. >> he had the ability to form the specific intent to kill, and he did have the intent to kill when he shot scott and mr. williams. >> reporter: in the end, three medical experts agreed. and most importantly, so did the jury. >> i understand that mr. horner saw things in iraq that were probably horrifying. but you know, so did we. one thing i know that he didn't see was the image of his father, you know, laying on the asphalt in a pool of blood like my mother saw. >> reporter: nick horner was convicted of murder. but the jury spared him the death penalty and sent him to prison for life. >> we all feel like we're doing a life sentence with nick right now. it's -- it's still a nightmare that we can't wake up from. coming up, making illegal meth is easier than ever. but it's also more dangerous. and guess who's left paying the bill? 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>> no. i was never around when david was making it. and i guess it was just something that if i didn't see going on i guess i didn't have to think of it as something that was that bad. >> she'd asked why we had everybody in suits with masks on. she said, what do you think, that stuff's poison in there? >> i'm not a bad person. i just ignored it because we needed the money. >> reporter: so you were selling the meth to make money? >> no. i don't sell anything. my husband did, and he got our electric turned back on. and it was going to -- it was going to be over. >> we'll pick our area with this frame. then we got a pattern that they make us swab. >> reporter: detective jason valentine uses a test kit to sample residue from a wall. >> add three or four drops to the test strip. >> reporter: what's the verdict? >> it's a positive test. there's been meth manufactured in here. >> reporter: with that and other code violations, kathy's trailer is about to be condemned. >> you're going to have to move out tonight. >> i don't have anywhere to stay. >> reporter: and then an hour and a half later kathy learns her daughter is being placed in protective custody. >> i don't care. you're not taking my child. you are not taking my child. she can go stay at a family member's house. i know what's best for my child. okay? maybe i made some wrong decisions. i don't care. but you're not taking her. >> reporter: authorities place the girl with her grandparents. >> oh, i'm so sorry. >> reporter: kathy's husband, david, will later turn himself in to police to face charges. as this tragedy plays out, it's a microcosm of meth's impact. >> it's hard to describe when you see the toll that meth labs take on a community. we're all losers in it. >> reporter: the drain on law enforcement. the cost of cleaning up the hazardous waste. and this night, a family torn apart. when we come back, a shake and bake survivor tells his story. >> looked like raw steak. >> i don't have feeling in that. >> and guess who picks up the tab? with the spark miles card from capital one, sven's home security gets the most rewards of any small business credit card! how does this thing work? oh, i like it! 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[ male announcer ] one pill a day. 24 hours. zero heartburn. more and more meth lab fires are leaving a wake of hard to treat burn victims. and it creates a multimillion-dollar financial burden on hospitals and taxpayers. amber lyon continues her report from rural missouri on the hazards of a do-it-yourself recipe for making meth known as shake and bake. >> there was a tattoo that covered the majority of my chest right here that was removed from the burns. and my throat, my eyes, the side, my ears. that, i don't have feeling in that. that's like a numb feeling. >> reporter: his name is dennis potter. more than 60% of his body was burned in a meth lab fire. >> looked like raw steak. have you ever skinned a deer? that's what it looks like. or have you ever skinned a cow or anything like that? >> reporter: dennis began using meth at 16. hooked on the intense rush. >> you think you're on top of the world and you're untouchable. and, like, you could make it rain or shine when you want. you think you're god when you're on it. >> reporter: god? >> yeah. more or less. you think you're the president of the world. >> reporter: he dropped out of high school, where he was known as one-punch potter. he then started making meth. shake and bake. a new recipe that combines all the ingredients into one bottle. highly risky because it can blow up. but so convenient, you can make it in your car. >> just driving along, shaking it and set it between your legs and loosen the cap so you can release the pressure and then cap it back off and keep shaking. >> reporter: were you ever worried this could explode on your lap? >> no. you really don't think about that. you think about when you're done how high you're going to get off the meth. >> reporter: the fire happened making meth in his trailer. >> the jug was on fire. and when my buddy handed it to me to get rid of it, i kind of shoved him out of the way because i knew it was too late. so i shoved him and, boom, it blew up. i remember seeing a flash of light. a big flash of light. and i remember being on fire for about five minutes. >> my feelings that night were primarily rage. >> reporter: next-door neighbor tom cisco has two young children. >> their concerns were that they were going to lose all their toys and their home where they lived. my concern? the lives of my babies. i mean, that was my main concern. >> reporter: luckily, the fire was contained. his children were safe. but the parents of 20-year-old dan mittenburg several counties over were not so fortunate. >> this one is a scholarship award that he'd gotten to go to linn. >> yeah. >> reporter: linn technical college. dan rented a room here, a mile from the campus, to avoid parties and drugs. >> he wanted to go to school to learn. >> reporter: but down the hall, a meth cook. when the lab caught fire, he got out. dan did not. dan's parents remember the last time they talked. >> he called me and told me, i'll see you friday night, you know. and -- and -- >> he was supposed to help tom move. >> and he says, "i love you." >> reporter: the fire in dennis potter's trailer almost killed him, too. >> i could see the fire. it's burning my face. and the fire's coming up, coming up, and it's burning my mouth. and i'm breathing in the flames. and i can feel the flames burning me, burning my throat. and on the inside i could feel it in the inside on fire, too. >> reporter: he was taken to mercy hospital in st. louis with second and third-degree burns. plastic surgeon dr. michael smock. when you first saw dennis, were you thinking he was going to survive? >> he was clearly at risk of dying. >> i love you. >> i miss you. >> reporter: at his bedside, the grandmother who helped raise him. >> every day i look at my grandson and i cry. he doesn't see it, but it's there. >> reporter: shake and bake burns from chemicals and heat are especially complex. >> i'll slant you back, okay? >> what we do is we first have to cut off the burned skin. >> i'm just going to wrap your pinky and your thumb. >> and we use one of these kinds of knives to shave the burned skin off of the burn area. >> reporter: dennis's family took pictures as he had skin grafts. >> you move this over an unburned part of the skin, and it shaves off a thin layer of skin. that's the skin graft. >> they cut it from my thighs. little chunks of skin. little square chunks. >> at one point we had to sew his eyes shut as we placed skin grafts on his eyelids. >> the bandages and the way the skin looked and the way it just -- it looked like freddie krueger. >> reporter: it's been two years. a remarkable recovery. but it came at a price. and not just to dennis. dennis was on medicaid. courtesy of taxpayers. there are some taxpayers who will watch this and be upset. >> hell, yeah. i say tha