preservation, it doesn't matter how much someone does 13, 14 years later in an investigation, if you don't have the evidence, you don't have a case. it's usually easy to figure out how a criminal enters a crime scene. but in this case, it was far from clear. it looked like the killer vanished in thin air. and perhaps he had. >> getting into medical school. it's the hope and dream of thousands of students who apply each year, then pray they'll be accepted. michael andrade was one of those hopefuls. >> he really wanted to be a doctor. he really wanted to help people. just recently, my mom told me, she used to tell him, don't worry, michael, all your hard work's going to pay off, because

he worked really hard at school. >> in 2005, michael was a premed student at st. mary's university in san antonio, texas. he decided not to live in the dorms, so he rented an apartment a few miles from campus. >> he actually chose that apartment because it seemed more family-oriented than the other apartments. he said that was the one he felt safer in. >> one morning in february of that year, workmen smelled smoke coming from michael's apartment. >> they noticed that the windows were coated with soot. and when they went to the door, it was unlocked. >> and as soon as they opened the front door, smoke came billowing out. >> they were forced out because of the smoke, and when they went back in, they found mr. andrade laying on the bed. >> michael andrade had been strangled to death.

>> his body was somewhat burned but very little compared to if the fire would have taken over. he was found with one of his arms, his right arm, in fact, back behind him, about belt high. it appeared he had been at some point tied up with his hands behind him. >> there were no signs of forced entry, but electronic equipment was missing. >> there was a entertainment center that had speakers hanging off the front of it which appear to have been connected to something, and that item was missing. >> on the computer desk was a perfect, you know, demarcation of where a computer would have sat. >> this meant that the computer had been stolen after the fire started, and the fire was set in three different locations. >> arson investigators gave information from the beginning that the fire probably was not started with an accelerant. it wasn't gasoline, it wasn't lighter fluid, anything that would create big flame-type -- a big flame-type fire. >> a winged back chair placed in

between the kitchen and dining area was the site of one fire. the foot of the bed was another. and the third fire started on the floor of the bedroom closet. >> i have watched a lot of forensic shows, and i knew that that seemed like a coverup. that when there's three points of fire, one person's not going to -- the person who's obviously passed away was not the person who set it, that there was obviously going to be someone trying to cover up whatever evidence was in the apartment. >> michael had been wearing boxer shorts and a t-shirt, an indication he might have known the perpetrator and willingly let him or her inside. >> he knew them and was comfortable enough around them to be just in his underwear. if it was somebody that he didn't know, everyone was certain that he would have put on more clothing before he answered the door. >> with no forensic evidence,

investigators hope that the stolen items might lead to the identity of the killer. >> there was always a chance that something would happen, something would break later, someone would brag about the crime, someone would come across the stolen material or stolen property and bring that back and we could track it back that way. >> or maybe there was evidence in the apartment that they couldn't yet see. anybody have occasional constipation, diarrhea, gas, bloating? one phillips' colon health probiotic cap each day

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at michael andrade's autopsy, the medical examiner confirmed what investigators already suspected. >> she did find that he had been murdered before the fire was set because there was no smoke in his lungs. >> the deposit of soot across the body indicated that he had actually died in that face-down position, because the soot deposition was much more prominent across the back of the body. >> the cause of death was strangulation with a piece of cloth ripped from the bed sheet. and dr. dana also found fiberglass insulation on the body. this was unusual since there was very little structural damage caused by the fire. >> the material deposited was there alone.

there's a possibility that it had been deposited by the perpetrator when the deceased was strangled. it's unusual you would see just the insulation material without this other debris, such as wood, burned wood, nails, screws that have come out, and even fixtures out of the ceiling. >> in their search for suspects, investigators couldn't find anyone who had a motive to kill michael andrade. >> he never had no enemies. i never seen him mad at anybody, upset about anything. that's a person you don't even think anybody would have anything against him. so i had no idea. >> investigators discovered one person who was apparently angry with him, his longtime girlfriend, a fellow student, 22-year-old lilly mesias. >> i do remember quite a few fights between the two of them where he'd be very upset, either hurt or mad at her. i don't know exactly what would happen.

it was just they would have problems and you could tell. >> investigators found a voice mail from lilly to michael left at 8:30 that morning. >> she had left a message on michael's cell phone indicating that they were having problems and that she was done with their relationship. >> was it possible that lilly went to michael's apartment afterwards and there was an altercation? >> at that point, combined with the fact that it seemed like michael may have known the person who did this to him, she was initially a suspect. >> but lilly had an alibi. she was working at her part-time job on the morning of the murder and was eliminated as a suspect.

>> she was very forthcoming. she was willing to give us a statement, willing to allow a search of her apartment, willing to allow us a search of her vehicle. >> michael's sister stephanie provided the first solid lead. she said michael complained about a man he saw around the apartment complex. >> the guy would just talk to him but the guy made him uncomfortable for some reason. he didn't say why. the guy never said anything suspicious to him or anything mean, but he said he always felt a little uncomfortable or a little uneasy around the guy just because his character seemed little bit off. >> unfortunately, michael never identified the man, provided a physical description or mentioned where in the complex he lived. >> right at that point, investigators had merely the crime, the crime scene, and a very large universe of potential suspects with not a whole lot to go on pinpointing a specific person. >> with no other suspects for the murder of michael andrade, investigators appeal to the public for help. four days later, an anonymous tipster called. >> the crimestoppers tip was amazing in its detail. >> the tipster told police the killer didn't enter andrade's

apartment through the front door or even a window. he entered through an attic crawl space. >> the tipster knew that mr. andrade's laptop was missing, knew about the contents of the laptop, which was never public information. >> you really have to question, how would somebody know this kind of information? [ ambient street noise ] ♪ ♪ ♪ abe! get in! punch it! [ male announcer ] let quicken loans help you save your money with a mortgage that's engineered to amaze. thanks, "g."

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investigators got an anonymous tip in the michael andrade murder investigation that the killer entered michael's apartment through a crawl space in the attic. sure enough, investigators found a panel opening to the attic in the ceiling of michael's bedroom closet. when investigators checked it out, they discovered that someone could access other apartments through the crawl space. the insulation was only matted between michael's apartment and apartment number 1002. >> none of the insulation above any of the other apartments had been disturbed. the only apartment that had been disturbed was michael andrade's apartment.

>> the tenant of apartment 1002 was 23-year-old maria solis, a single mother who lived there with her 3-year-old son. when questioned by police, maria claimed she didn't even know michael andrade or where he lived, but investigators didn't believe her, so they took the unusual step of confiscating maria's vacuum cleaner and the clothes in her hamper. investigators found a pair of men's jeans, and on those jeans were tiny glass fibers. the small air pockets within the glass had expanded, creating a distinctive football shape. this was fiberglass insulation that had been in or near a fire. >> the evidence was not destroyed. it was simply charred. this gave it unique properties, something that i could compare

back to with any standards that were found at the scene. >> the charred insulation on these jeans was consistent with the charred insulation found on michael andrade's body. >> the insulation was unique. it was burnt insulation. so, it wasn't a situation where the person could say i'd been working at a construction site, that's how i got this insulation on my clothing. >> wrapped around the spool of the vacuum cleaner, investigators found highly distinctive thread. black polyester fibers were wrapped around cotton fibers, then colored with an unusual combination of dyes. this thread was consistent with thread found around michael's neck. it matched his bed sheet which had been torn and used as a ligature. >> microscopically, it was the pattern that the threads had that were able to give me that

distinguishing or that unique appearance that associated with the bedding material. >> also in maria's apartment, investigators found a video camera and keys to a ford truck. the video contained images of michael andrade's family, proof that the camera was michael's, and the car keys were michael's, too. >> michael andrade's truck was a ford f-150 and these keys were ford keys. went down with the alarm remote on the set of keys and opened up his truck. >> investigators confronted maria solis and wanted to know who owns the men's jeans found in her hamper. after she was threatened with prosecution, maria solis changed her story. she now admitted she had a roommate, 25-year-old joe luna.

>> she met luna over the internet and seemed to me to be desperate to be in a relationship with a man and latched on to joe luna in what i believe was a very manipulative relationship. >> maria claimed she knew nothing about joe luna's criminal past, that he had served five years in prison for carjacking and aggravated assault on a police officer. and joe luna was wanted for a series of home invasions that bore a marked similarity to the michael andrade case. >> he would break in, cut bed sheets up, tie up the people who were at the house with those strips of bed sheets. >> he terrorized five separate people, three of whom were families with children.

he tied them up. he used weapons. he threatened them. he stole from them. >> brooke envick was a victim of one of those home invasions. >> it's just indescribable. i mean, you feel like your home is where you're safe. >> after the robbery, brooke found forensic evidence the perpetrator had left behind. >> we noticed that two cigarette butts were in the garage. we don't smoke and none of our friends who had been at the house recently smoke. >> dna from the saliva on the cigarette butts matched joe luna. >> police! >> just five days after michael andrade's murder, joe luna was arrested and charged with the crime. >> did you kill your neighbor? >> i'm not going to kill nobody.

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the forensic evidence painted a vivid picture of joe luna's movements on the morning of michael andrade's murder. prosecutors believe joe luna spent most of his time inside

his girlfriend's apartment since he knew there were warrants out for his arrest on the robbery cases. with nothing to do, he discovered there was an attic and crawl space above the apartment. so, he looked around and discovered there was another apartment just 16 feet away, michael andrade's apartment. prosecutors believe he opened the panel in michael's bedroom closet, and when he didn't hear any sound, dropped in. but michael was sleeping and the noise woke him up. there was a struggle. luna tore the bed sheets, bound michael's hands behind his back, and strangled him to death, fearing that michael could identify him.

to mask the evidence, he set fire to the clothes in michael's closet and returned to his girlfriend's apartment through the crawl space. when he didn't hear the fire alarm sound, he suspected the fire went out, so he returned to michael's apartment to start the fire again. he stole michael's computer, electronic equipment, and his car keys. before leaving, he set the two additional fires. when luna returned to his girlfriend's apartment, he shed fibers from michael's apartment which he tried to remove with his girlfriend's vacuum cleaner. and he put his jeans into the clothes hamper, which had the burned insulation on them. >> having that forensics

evidence in your back pocket as an investigator is just something you can't overcome. when it's on your clothing, there's a real hard hurdle to overcome to say i didn't do it now. >> during her police interrogation, maria solis eventually admitted that luna had confessed. >> he's like, well, i just went into his apartment. and he's like, well, somebody was there when i got there. i'm like, okay. he's like, well, they saw me. he's like, so, i had to do what i had to do. i'm like, what are you talking about? >> what did you think in your mind that he did? >> that he had hurt somebody. that he had done what he did to this boy. i don't like to say the four-letter word. >> i need you to say the word. >> that he had taken this person's life. >> joe luna headed for trial insisting he was innocent, but the forensic evidence caused him to reconsider.

>> the fiber evidence that was found and the fiber evidence that i had looked at was apparently so compelling that the defendant didn't want to continue on with this case, which is quite unusual for a capital murder trial. >> so, luna changed his plea to guilty and admitted what he had done in open court. >> mr. luna, how do you plead to the charges of capital murder? >> guilty. >> he testified that he enjoyed it, that he lived for the adrenaline rush that it gave him to victimize people and to get away with it. i cannot fathom the terror that that young man went through. and really, there could be nothing worse than seeing a joe luna walk out of your closet. >> in march of 2006, luna asked the jury to give him the death penalty.

they willingly obliged. >> there are certain people in our society that have absolutely forfeited their right to live among us by their own actions and by their own decisions. joe luna is one of those people. >> ironically, joe luna tried to cover up his crime by burning the evidence, but he didn't destroy it. instead, he made those tiny glass insulation fibers more distinctive. >> it was actually the last way that i thought they would catch him. that was furthest from my mind it would be in a vacuum. >> you have to have the forensics. you have to have the evidence that can't skip town. you have to have the evidence that can't lie to you. >> as my old professor once said, there is no such thing as a perfect crime.

that's, you can plan, you can calculate, you can try to manipulate the circumstances or the surroundings, but you will always leave a piece of trace evidence behind. love you! >> a 13-year-old girl went missing from her colorado home with little evidence to explain what happened. the investigation dragged on for two long years, until an alert fingerprint examiner found a serious flaw in the system. >> september 7th, 1991 was like most other days for the church family. diane church got the kids off to school, ran errands, went grocery shopping and planned to spend a quiet evening with her family.