Inside Cold Case Investigations

When he began investigating the gruesome slaying of an unidentified girl who became known as "Precious Doe," Sgt. David Bernard initially thought he would be able to find her true identity and her killer within days, perhaps weeks.

However, it has been more than 2½ years since police found the girl's naked body and severed head in a wooded area in Kansas City, Mo. Despite some national coverage and features on America's Most Wanted, Precious Doe's true identity remains a mystery, and there have been no arrests in her slaying.

"The key here is getting an ID on this little girl. That's the main thing," Bernard said. "Without an ID, I can't make any forward progress on this case. When I first got the case, I thought that perhaps the girl is local, from the area, that someone would come forward and we'd have the girl ID'd within days. But more than two years have passed and we still don't know who this little girl is and that makes me think maybe she wasn't from around here.

"The frustrating part is that you think you're just one tip, one clue away and that all it takes is for the right person to come forward," Bernard continued. "With homicide cases, many of the victims tended to put themselves in danger by being involved in drugs, those kind of things. But this was a little girl who could not defend herself. … And that's what keeps me and my team going."

Despite the lack of progress, Precious Doe's slaying is not considered a "cold" case and has not been transferred to the Kansas City Police Department's cold case squad because Bernard and his homicide unit are still receiving tips. But the trail is considered cold in many lesser-known unsolved slayings that have been sent to cold case squads.

The Last Defenders of the Forgotten

Most cold case homicides do not receive national media attention. Cold case investigators consider themselves the last defenders of these often-forgotten murder victims. When the original investigator is no longer on the case, the cold case unit looks at the file with a fresh pair of eyes and searches for clues or potential leads that may have been overlooked.

"What we do when we get a case is review it from start to finish," said Sgt. John Jackson, who heads the Kansas City Police Department's cold case unit. "Often there will be something that was overlooked. We look at the physical evidence, where some more information can be taken from it, such as DNA evidence. We look for any relatives, ex-wives, friends, business partners that we can locate or do follow-up interviews with and whose memories we can jar and who may have that key piece of information they didn't offer before."

Cold case investigators, Jackson said, like to pursue numerous different leads simultaneously because it helps them eliminate various theories. It also may prevent them from inadvertently tipping off potential suspects who still live in the area.

"We like to answer the questions before they're asked," Jackson said. "When you start digging around on a case that no one has talked about in a while, word spreads fast and you don't want your potential suspect getting to people before you do, getting them to clam up. … It's very frustrating when the people either don't want to talk or you can't find that right person with the information you need."

The Changing Face of Homicide

Unsolved homicides — slayings where law enforcement officials are unable to make an arrest — appear to be on the rise.

According to Bureau of Justice Statistics, in 1990, police made arrests in 72 percent of the homicide cases in the United States. In 2002, investigators solved 64 percent of homicides. Experts say uncooperative witnesses and the changing nature of homicides have contributed to the rise of unsolved slayings.

"Over the past 20 years, we've seen a decline in murders within families, among married couples. Those are typically a slam dunk for the police to solve," said James Alan Fox, professor of criminology at Northeastern University. "We've seen a growing number of youth homicides, drug-related homicides, gang homicides."

The DNA Revolution

Still, evolution of forensic technology — particularly DNA technology — has led to arrests in many cases where the trail had been considered hopelessly cold.

The 1993 strangling of Mia Zapata, the lead singer for up-and-coming alternative rock band The Gits, baffled Seattle police until last January, when authorities said DNA linked Florida fisherman Jesus Mezquia to the slaying.

Detectives from the King County, Wash., cold case squad had submitted the DNA profile of evidence from saliva found on Zapata to the National DNA Index System in November 2002. Mezquia had submitted a sample as part of a previous, unrelated arrest in Florida.

According to a criminal complaint filed against him, in July 1993 Mezquia was living within walking distance of the area where Zapata was killed. He has denied even knowing Zapata, much less killing her, but cannot explain to investigators how his DNA wound up on her body. Mezquia is currently awaiting trial.

DNA evidence led to the 2001 arrest of Gary Ridgway in the Green River slayings, which claimed the lives of 49 Seattle-area women, including several prostitutes, in the 1980s. In November, Ridgway confessed to killing 48 women and subsequently received multiple life sentences in prison in a plea deal to avoid execution.

"Without a doubt, DNA evidence has been the biggest advance in cold case investigations," said Jackson, of the Kansas City cold case squad. "And there are advances being made every week. It has enabled a piece of evidence that detectives were not able to use 20 years ago to become a crucial part of the investigation."

Hope Amid an ‘Emotional Roller Coaster’

Jackson said he has six detectives in his cold case squad and each juggles, on average, four investigations. All are seasoned homicide investigators: The least-experienced member of Jackson's squad was in the homicide unit for nine years.

He stressed that cold case investigations are not as glamorous — nor nearly as quick to resolve — as the ones viewers love to watch on television.

"Nothing happens overnight," Jackson said. "This is not what you see on CSI or Cold Case, where cases are solved in an hour. Real police work takes time."

Meanwhile, Kansas City's Sgt. Bernard maintains that he and his investigators are hopeful that they will — eventually — uncover Precious Doe's identity and find her killer.

Officials are not even sure of Precious Doe's precise age. They initially estimated that she was between 3 and 6 years old at the time of her death. An examination by a forensic dentist released in September found that she was 3 or 4 years old when she was killed.

In September, the Kansas City Police Department unveiled a new bust of the slain child created by the FACES Laboratory at Louisiana State University. The bust was constructed using the girl's skull as a model and is considered the most realistic portrait of the child to date. Bernard hopes it will yield more clues.

"The case has been an emotional roller coaster," Bernard said. "But there are no plans to send this to the cold case squad because we're still getting tips. All we need is that right person to come forward."

Anyone with information about the Precious Doe case should contact the Kansas City Police Department's Homicide Unit at 1-800-399-8517.

ABCNEWS' Pierre Thomas contributed to this report.