>> the real clincher was the shoe print that left a piece of evidence that you cannot deny. it's there in black and white. up next, he promises to avenge his sister's murder. >> i prayed to god that i would be led to be in the right place at the right time. >> for years, he tracks her killer without success. >> every day was another blow to the stomach. >> somewhere deep in the houston crime files are the secrets to solve the case. he just had to find them. >> houston had 500,000 prints. everybody has ten fingers. that's 5 million prints. >> 34 years later, investigators find the answer. >> i want to know who killed diane. in december of 1969, diane maxwell pulled into the company parking lot in houston, texas.

it was sunday, and downtown was virtually empty. diane worked for the southwestern bell company, and her shift started at 1:00 p.m. but she never made it inside the building. a half hour later, a homeless man saw someone walking away from an old shack next to the parking lot. >> he walked back to the shack and walked very close to him and got a good look at him and went on to the shack, and he found this young girl lying on her back with her hands tied behind her back, and he asked her if she had been assaulted. shed a said yes. >> she asked him to untie her, and he said no. but he agreed he would go call the police. >> tragically, by the time police arrived, 25-year-old diane maxwell was dead. >> she was lying on her back, bra pushed up, a small wound just above her navel, probably

an inch in width. >> diane was just 25 years old, a single mother of a 4-year-old son. >> well, i will tell you that it was the most devastating thing i had ever experienced. my first reaction was denial, that there's no way that, you know, diane could be dead. >> in a search for evidence, police scoured the wooden shack. among the debris, they found a rumpled pink blanket and a man's gray suit coat. >> it had been used as a storeroom for a service station. and everything imaginable was in there from service manuals to old oil cans. >> the only witness was the homeless man, willie bell. >> and that the only physical description was that it was a description was it was a black male with an afro haircut. >> there was no money in diane's purse. her car keys were missing. and her car, a new red mustang, was gone. police found it nine hours later, a mile away.

>> the car was locked. the keys were in the ignition. >> so, it was obvious that whoever killed diane, you know, took her keys and then took her car. >> at the autopsy, the medical examiner found evidence that diane had been sexually assaulted, and she had been stabbed just once, with surgical precision, severing an artery. one possibility was that the killer was a medical professional. and since one of the state's largest prisons was just 70 miles away in huntsville, an ex-convict could have been responsible. >> houston was the first stop. and usually, they had just the clothes on their back and probably $25 and wouldn't have been enough to live on a day or two until they would start and do other endeavors. >> diane's brother vowed to help catch her killer. are you so congested...

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the senselessness of diane maxwell's murder shocked everyone -- friends, co-workers, and family. >> i knew that she had been

attacked and murdered. and i really never asked for any other details, just because i didn't think i could really deal with it. >> the last thanksgiving we spent together, diane had gotten me off to the side and said, you know, david, if something happens to me, i want you to raise my son. and i said, okay, well, i will. and that was less than a month before she was killed. >> more than 20 of diane's co-workers at the phone company quit their jobs. many of those who remained armed themselves with ice picks and knives. >> it was very, very hard. the news carried quite a bit of information about it. and you're seeing it on tv. and you're reading about it in the paper. and i'm getting phone calls, even phone calls from people i don't know. >> but the killer had stolen diane's red mustang and abandoned it, leaving it a mile from the crime scene. >> i printed the steering wheel, inside the driver's door, and

the t-shift. the next day, went back over it, and was successful in getting i would say 12 or 15 identifiable latent prints, very good prints, and many of them looked fresh. >> the prints, three partial fingerprints and a partial palm print, did not match those of the witness, willie bell, and he was eliminated as a suspect. in 1969, before computers, someone had to literally compare a print visually to all the ones in the houston crime files, and there were millions of prints. >> let's just say houston had 500,000 prints. well, if you think everybody has ten fingers, that's 5 million prints. now, if i were to try to take that latent and look at 5 million prints, well, i don't know how many lifetimes it would have taken. it would have never happened. >> instead, police compared the prints from diane's car to everyone arrested for a crime

committed after her murder. police also questioned the people who loitered in the downtown area. >> they were looking for a black male. they knew that from willie bell told them it was a black male that had been seen raping diane. >> they did get a few leads, but they didn't pan out. nothing pointed to the person that actually committed the offense. >> since the fatal wound was made with surgical precision, police also focused on health care workers as possible suspects. >> they just started dragging everyone, all the black males, downtown and had them fingerprinted. and they were doing some things that would not be accepted today. >> i thought that, honestly, that the person just slipped through the cracks. >> diane maxwell's murder started to look like a random homicide, the hardest kind to solve. >> everyone assigned to the homicide division at the time, they were like 30 detectives,

they all worked the case. but as time goes on, as you know, and the leads diminish, there just comes a point in time where there's just -- there's no more trails left. >> each week, as more and more fingerprints were added to the houston files, examiners would compare those to the prints from diane maxwell's mustang, with no success. >> we were confused. we thought -- we expected that it would be resolved. you know, and you had had the funeral and everything. then you did begin to think about the resolution. and so it was very, you know, upsetting and hurtful that there was no resolution. >> eventually, the trail of diane maxwell's killer turned cold. and for 17 years, there was virtually no progress. nevertheless, diane's father never lost hope. >> every time i would see him, he'd say, son, i want you to solve this case before i die. i want to know who killed diane.

>> our parents were quite elderly at the time. and so, i know that was an impetus, but i think it was just an ongoing impetus. >> so, at the age of 37, david maxwell was accepted into the oldest and most exclusive law enforcement agency in north america, the texas rangers, an elite group with only 134 members. >> i thought about it a great deal, that if i became in law enforcement, if i was able to eventually get into the texas rangers that -- and it remained unsolved, that i would be able to reopen the case and eventually solve it. >> and by this time, the houston police department had recently purchased an afis system, the automated fingerprint identification system which can instantaneously compare unknown prints to those in the houston database.

david asked the department to run the unidentified prints found in his sister's car. at the time, they actually had to be traced. >> we don't do that anymore. but years ago, the traced image, we just had better luck with the tracing than the direct image. the image just wasn't as clear as it is now. >> unfortunately, there was no match. >> i began to think that maybe he was dead, because i couldn't imagine that you would commit that type of crime, which was probably random, and never commit it again. >> and the case turned cold again for another 17 years. it was becoming clear that david maxwell would need help.

for more than 30 years, david maxwell was haunted by his sister's murder and still hoped to find some way to solve it. >> he had been successful in solving a lot of very complicated crimes, and i know that this was really important to him to try to solve this crime, because, of course, this was very personal. and, you know, he felt very deeply about it. >> and he had promised his father he would solve the murder before he died. by this time, his father was

close to 90 years old, and time was running short. >> and he would tell me that he would dream of seeing diane. and that's all he thought about. he said, that's all i can think about is diane and this case being solved. i want to know who killed her before i die. >> with nowhere else to go, david turned to his friend, jim ramsey, a veteran homicide investigator with the houston police department. the two had known each other for years, but david never told jim about his sister's murder. >> i was shocked. i was amazed that anyone could hold that in and not talk about it. but if anyone could do it, it would be david. >> i saw no need to tell people about what had happened in my life. i wasn't looking for sympathy. >> david could have had just about anybody in the state of texas work that case. i really considered it, i guess, a privilege when he asked me to look into it. >> ramsey's first priority was

to examine diane maxwell's clothing. >> if we could do the dna from the sexual assault and to get that and put it in the database, because now, all the offenders as they go to prison, they're taking dna samples. and we're getting a lot of cold hits on the dna database. >> but diane's clothing was gone. to their shock and dismay, it had been thrown away. >> over a period of years, i guess folks in the property room just had to make room for new property coming in. >> next, ramsey tried to interview the only witness to the crime, willie bell. >> we tracked him out to an address in california. and we eventually learned he had died back in, i think, the mid-'80s. >> then things went from bad to worse. the crime scene photos and the negatives were also gone. apparently, in violation of

police policy, someone had sold them to the british crime magazine "master detective" in 1971. when contacted, the publisher no longer had the pictures or negatives. all they had left was a single copy of the magazine. >> i asked them to send it to me because i didn't have any pictures of the crime scene. and they were hesitant to do that because that was their only copy. so i asked them to please, you know, make copies of the photographs. >> the photocopies of the magazine pages were virtually useless. and then jim ramsey and david maxwell got even more bad news. the killer's fingerprints found in diane maxwell's car that were supposed to be in her police case file were also missing. >> it was just like every day was another blow to the stomach. >> i knew they existed. and now they're gone. so, yeah, i was pretty upset about it.

>> with all the evidence gone, david now had to tell his father that the case might never be solved.

investigators literally had no evidence from diane maxwell's murder. the crime scene photos were gone.

the victim's clothing had been discarded. the only eyewitness had died. and the killer's fingerprints were missing, presumably misfiled in one of the thousands of open case files in the houston police department. >> everybody, at some point in time, was looking for that case. so, it wasn't like, okay, well, we'll just do it in our spare time. somebody every day was looking for that case. >> i guarantee, they went through many, many files. a tremendous undertaking. >> debbie and i worked together for 11 years. rumor has it that she went to the director of the latent lab and told the director that sergeant ramsey was threatening an ied investigation if they didn't find that print. well, i never once said that. >> i respect authority, but i don't mind challenging authority. >> but whatever happened, it got them off of dead center, and there were several people that were assigned to go through every hpd case looking for prints. >> after months of looking

through all of the case files, someone finally found them. >> they just put it in the wrong file. you know, it was just a clerical error. >> of all the evidence lost, at least the fingerprints had been recovered. by this time, the year was 2003, and sophisticated, computerized fingerprint systems were everywhere. jim ramsey had the prints from diane maxwell's car compared to those in the texas statewide database. unfortunately, there were no hits. undeterred, ramsey ran the prints through the fbi's national database. this time, there were 20 potential hits. all 20 were then examined visually, and one stood out. >> when this print came up, it was like, oh, my gosh, this looks awfully good. this looks like we're going to have a hit. >> the print belonged to

58-year-old james davis, a career criminal. >> i identified him four different times. i identified them, i think, fingers -- right index, right middle, right ring, and then the right palm. >> it's hard to really describe how i felt, but i was absolutely elated about it. >> james ray davis spent the majority of his adult life incarcerated, auto theft, forgery, assaults. >> davis was living in a housing project on the texas/arkansas border. he had been out of prison for about ten years following a conviction for abducting a young girl. detective ramsey knocked on his door. >> i said, "mr. davis, i'm from the houston police department." and you could tell his demeanor changed drastically. he just stared at me. >> ramsey pulled out a photo of diane's car. davis didn't want to look at it. >> he said, "i've never, ever

seen that car." well, that's strange. it's a red mustang. you've never seen a red mustang? then i pulled out a picture of diane that david had given me and i handed it to him. but he wouldn't take the picture. i tried to hand it to him, he wouldn't take it. >> davis initially denied any involvement. but when told of the fingerprint evidence, he confessed. >> i'm very sorry that it happened, and i've cried and i've prayed what i did wrong. >> he'd been out of prison five days when he killed diane. and his life was a lifetime of crime. >> after more than 30 years, the mystery was finally solved. >> well, my father was ecstatic. it just was a huge boost for him, you know, that they knew who it was. >> i've worked scores or hundreds of murders. and they're all important to me. but it's not very often that you're personally touched by them.

>> davis said his primary motive was robbery. when he saw diane get out of her car, he abducted her at knifepoint, and took her to the wooden shack. he admitted robbing her, but denied sexually assaulting her, although the evidence clearly showed that he did. then he stabbed her to death and stole her car. he abandoned the mustang across town and left his fingerprint and a palm print. although it took almost 35 years to find him, his fingerprints on file had not degraded. >> if it had not been for the afis system, he would have never been identified. >> on january 15, 2004, james davis pled guilty to murder with malice and was sentenced to life in prison.

>> i never saw remorse. not one time. the only time i saw remorse was when he came to court and he pled guilty, and a judge sentenced him to life. he didn't care about diane. >> diane maxwell's father lived long enough to see her killer brought to justice. >> this database has been such a boost to law enforcement, to be able to help solve these crimes that otherwise would go unsolved. and now with the dna database, and that's doing the same thing, i mean, it's just been a tremendous boost to those of us in law enforcement who work these kind of cases. >> investigators believe the conviction was the result of hard work, cooperation, and perhaps something else. >> i really think it's divine intervention, because i mean, look at it yourself. look at the odds that we had going into this thing. we didn't have a million to 1 chance we'd clear this thing. and i don't know, maybe because of the unselfish life that

david -- his career that david's committed to the people of texas, maybe the lord said, well, i'm going to give him a break. hello, everyone. thank you for staying with us. i'm natalie ail allen. we want to welcome our viewers in the united states and around the world for our continuing coverage of the earthquake in nepal. we have this just in to in the cnn newsroom. within the last few minutes, a major aftershock has hit nepal yet again. the u.s. geological survey says it was a 6.7 magnitude. we know that climbers on mt. everest are also reporting a series of new avalanches and rock falls. as y