Sometimes it takes a DNA expert. Sometimes it takes a ballistics team. And sometimes it takes an artist to catch a killer.
When the body of an unidentified 3-year-old girl was found floating in a box in Galveston Bay on the Texas Gulf Coast in late October, it was forensic artist Lois Gibson who helped break the case.
Despite the severe decomposition of the remains, Gibson examined photos of the body for facial landmarks to compose a portrait.
"From the photos I used, I was able to see the shape of the eye sockets, the size of the eye sockets, the ratio of the nose and the chin, the hair length and texture and color," Gibson told FOX News.
Within a few days, Gibson produced two portraits of the little girl, dubbed "Baby Grace," which were given to the media.
Three weeks later, an Ohio woman came forward to say "Baby Grace" looked like her granddaughter, Riley Ann Sawyers, who had recently moved to Texas with her mother.
DNA tests confirmed the girl's identity, and her mother and stepfather were arrested.
Unfortunately, not all forensic methods work as quickly or as efficiently as artistic reconstructions. Many crime labs in the U.S. are not well funded, often operate in old facilities and are typically understaffed.
Lack of money and training bog down many high-tech efforts to catch killers, and experts fear many crimes that could be solved remain on the books as a result.
Killer DNA Profiles
Most of today's forensic DNA experts test crime-scene samples using short tandem repeat analysis (STR), which examines the repetition of three adjacent nucleotides — the organic chemicals that make up DNA — within a DNA sequence.
This technique can create a unique genetic profile of an individual, which means it can help identify a killer.
For example, just two months ago Houston police finally solved the brutal murder of Sharon Darnell, who was only 14 when she was sexually assaulted and stabbed to death in an abandoned building in 1984.
Semen was found on her body, but tests at the time were unable to link it to the prime suspect, 23-year-old Frederick Johnson, who was let go for lack of evidence.
In May 2007, the Houston cold-case squad followed up with retired sergeant John Burmester, who had kept tabs on Darnell's murder ever since he was on the original investigating team.
Modern DNA tests showed the semen was indeed Johnson's, who by that time was already serving life for raping another teenager.
Blood found on his clothing in 1984 was also proven to be Sharon Darnell's, and Johnson, now 47, faces a capital-murder trial for her death.
"The good Lord works in mysterious ways," Burmester told the Associated Press in November. "I guess justice seems to catch up with people."
Newer DNA techniques enable the matching of four, not three, adjacent nucleotides — so-called "four-repeat" testing — which is even more precise.
"The new technology uses the same idea of testing, but it is at least 25 percent more accurate," says Dr. Paul Goldstein, a professor of toxicology, forensic science and genetics at the University of Texas at El Paso.
But law-enforcement agencies nationwide are being slow to update to four-repeat analysis.
"The trouble has to do with money," says Goldstein. "They would have to re-capitalize and get new equipment, and that's expensive, so they're staying with older technology that is at least 10 years old."
An even more sophisticated DNA-processing technique looks for SNPs (single nucleotide polymorphisms), the most basic kind of genetic change between two strands of DNA.
If a suspected killer has an identical twin, three- and four-repeat testing would not be able to distinguish between the two of them.
But SNP techniques analyze every single DNA molecule and would single out the killer.
To facilitate DNA retrieval and identification at the crime scene, NEC Corporation has teamed up with Aida Engineering to develop a briefcase-sized four-repeat DNA analysis system.
On-site results can be obtained in 30 minutes, whereas lab testing uses different equipment and takes at least a day, sometimes several weeks.
The new system performs several processes in the same unit, making it portable and easy to use.
But testing samples at the scene also greatly increases the risk of sample contamination, which would be costly to correct or might even render samples useless.
Biting the Bullet
In a fatal shooting, matching bullets to a firearm — known as toolmark analysis — can be key to catching the killer and is one of the roles of forensic ballistic experts.
Each gun leaves unique marks on used bullets and cartridge cases, which can directly link it to a specific crime.
In fact, modern ballistics matching helped crack another cold case.
In 1961, Columbia, S.C., taxi driver John Orner was robbed of $45 and shot in the back of the head, his body dumped by the side of a road.
A month later, Tennessee police picked up 18-year-old hitchhiking soldier Edward Freiburger, who had gone AWOL from Fort Jackson, just outside Columbia.
Freiburger was arrested for possession of a loaded .32 caliber pistol, which was confiscated.
Tests at the time indicated that the weapon used to kill Orner was of the same caliber, and probably even same make, as Freiburger's gun, which pawn-shop records showed he had bought for $52 only hours before Orner was killed.
But ballistics tests back then could not provide a definite match between the bullet, which had fragmented in Orner's skull, and Freiburger's gun.
Despite the circumstantial evidence, no charges were filed. Freiburger was freed after serving a year in Fort Leavenworth for going AWOL.
In 1997, chance encounters between a member of Orner's family, a police officer and a retired Army investigator who had worked on the matter in 1961 prompted re-opening the case.
This time, tests proved a conclusive match between the gun and the bullet. Freiburger was found living quietly in Indiana and brought back to South Carolina for trial.
In 2002, 41 years after the murder, Freiburger finally went on trial for Orner's murder. The jury took only two hours to find him guilty and he was sentenced to life in prison.
In this instance, police in South Carolina already had the weapon on hand when they reopened the case. But what if one gun is used to commit crimes in different cities or even states?
To share ballistics information, law-enforcement agencies in the U.S. and Canada use linked national networks running various versions of software called IBIS, for Integrated Ballistics Identification System.
It quickly matches bullets to known firearms using a database that stores and analyzes ballistic images.
All versions of IBIS, created and supported by Forensic Technology WAI Inc. of Montreal, Quebec, acquire and analyze spent bullets and cartridge cases.
An investigator in New York can retrieve a bullet from a crime scene and put it into IBIS, which can match it to any bullet fired from the same gun anywhere in North America over the past few years.
But even though Forensic Technology's latest version of IBIS uses three-dimensional images to match bullets, cartridges and guns, most law-enforcement agencies are stuck with what the company now calls its "Heritage 2D" system.
The 3D software creates a topographic map of the surface area of the bullet, and also allows quantitative measurement of the bullet surface, increasing the chances of finding an accurate match.
"Bullettrax [the bullet component of the 3D system] will be a long time coming to every courtroom," says John Nixon, an engineer with Athena Research and Consulting of Bippus, Ind. "It should be a useful tool for explaining things to the jury. We are only just seeing a limited number of labs providing digital photographs, about eight years after the technology became available."
It's ironic that in the world's richest country and top technological innovator, most police departments can't afford the latest crime-fighting technology. It would take a dramatic increase in funding to enable the cops to stay scientifically ahead of the bad guys.