Laser enhances image
In the Martinez case, forensic specialists applied super-glue (cyanocrylate) fumes to the print and rinsed the surface with rhodamine, a fluorescent dye. Then they exposed the print to the laser; the light was passed through an orange filter to maximize the illumination.
"For nonporous-type surfaces, like weapons or plastic bags, it's very effective," said Michael Murphy, supervisor of the latent print section of the California Justice Department's Bureau of Forensic Services in Sacramento. "There's a misconception that the laser develops the prints. It doesn't. It enhances the prints, which enables us to view or see the print."
For porous surfaces, such as cardboard, forensic specialists use several fluorescence-enhancing chemicals to bring out the prints.
Although the technique has become commonplace in forensics, many smaller police agencies simply do not have the funding or in-house staff expertise to lift prints of this sort, particularly older prints.
The air-cooled laser used by the state Justice Department was purchased about six months ago for about $54,000, Murphy said. Similar 5-W, diode-pumped lasers cost $30,000 and up, putting them out of reach for most smaller law enforcement agencies operating under tight budgets.
"This laser is air-cooled and plugs right in, so it's very convenient for the forensic work that we do," Murphy said.
The 3-ft-long device is not taken out into the field because it is considered too bulky. The forensics unit has used a small, 0.5-W portable laser in the field for the past 10 years. However, that device lacked the power to discover the latent print at the scene where Anthony's body was found.
Prior to purchasing the Millennia, the California forensics unit had used an argon, liquid-cooled laser that produces a similar beam to that of the Millennia. "That unit's not as advanced as the Millennia, but we're still going to use that in a different lab," said Murphy.
Typically, units like Murphy's are called in because they have the equipment and staff expertise to provide the service at no charge to police agencies. Everyone on his eight-member staff has at least 15 years of forensic experience, including experience in the use of photonics.
"We use [lasers] daily," said Murphy, a 23-year forensics veteran. "We handle about 2000 cases a year, and we're swamped."
One of the most notable cases where photonics made a difference occurred in 1991, when three armored car guards were murdered with their own weapons during a robbery in Vallejo, Calif. The perpetrators had wiped down the prints on the guns and even the handles of the bolt cutters they used in the robbery. But using photonics technology, the California forensics lab was able to pick up a print left on the blade of the bolt cutters. Three years after the robbery, that single fingerprint led to the arrest of four men in connection with the crime.
The FBI's central forensics laboratory in Washington is equipped with two argon lasers, Spectra-Physics 2030 models, which get extensive use. The FBI's 100 examiners use photonics technology thousands of times a year, according to Tim Trozzi, a supervisor in the FBI's Latent Prints Div. Trozzi said that portable lasers were utilized in the field in previous years but that they had broken down and had not been replaced.
The New York State Police are leaning toward using alternative light sources that go under names such as Polylite and Lumalite to highlight prints, according to Lt. Vincent Rossetti. These light sources can illuminate under more wavelengths than standard lasers can, making them more efficient and convenient, he said.
Meanwhile, state police officers use a 12-year-old liquid-cooled laser in their new Albany laboratory. Three more lasers are scattered among the state police's nine regional troop headquarters.
The next frontiers
Although lasers have become established tools in the forensic arsenal, developments in digital photography and computerized communications are the next frontiers for forensics technology, Murphy said.
"We have the technology now to digitally photograph a print, send it by laptop computer to Sacramento and have an ID before we leave the crime scene. That is new to the fingerprint industry."
Digital still cameras produce instant pictures at the scene. A tentative identification can be readily connected to computers for transmission into California's 3-million-plus felony database. The system also has the capability of linking up with other states' computerized databases.
That fast turnaround time can mean the difference between apprehending a dangerous criminal and having him slip through officers' fingers.
In the Martinez case, no fingerprint match has been found yet, but sheriff's deputies are still hopeful. Authorities are slowed somewhat because not all states have computerized registries of known felons.
Murphy said a national registry of felons is likely to be established in the near future, once each state's computer system learns to "talk" to others.
"At some point, we'll get somebody," Murphy said. "We've just got to look at the right guy."
Return to page one.