Lighting the Laser Lens

Evidence collection has benefited greatly from lasers.

Lasers are nothing new. They've been used in labs for years, says Michael Kauf, senior product manager for Spectra-Physics, a division of the Newport Corp., based in Irvine, California. Portability is what is new.

Thanks to Newport Corp.'s Reveal system, crime scene investigators can bring all the advantages of technology previously available only in the labs out into the field, he says.

Reveal is a portable, continuous wave, laser-based system that uses thin-disk lasers. Packaged in a small flight case-like package on wheels, it is easily transported in any vehicle, explains Kauf.

The Reveal system solves issues such as overlooked evidence; evidence found on heavy, bulky or difficult-to-extract objects, making it challenging to safely send to the lab; or evidence that is damaged or cross-contaminated during collection and/or transportation. Because of its portability and design, says Kauf, Reveal lays these issues to rest.

The Reveal system consists of a DPSS laser (with diodes that have a lifetime of more than 10,000 hours), 22 feet of fiber optic cable and a wand — ergonomically designed — with zoom options. The thin-disk crystal creates a continuous bright-green laser light at 532 nm. Reveal, works from a conventional 110- or 220-volt power outlet and requires no warm-up time.

Along with improved (compared to ALS) identification of latent fingerprints, Reveal uncovers evidence such as blood, semen, saliva and sweat, bone, and teeth and skin fragments, and is unhindered by obstacles such as fabric or dry, uneven surfaces.

As of this writing, there are 10 Reveal systems in use, including two in Canada. The Royal Canadian Mounted Police (RCMP) uses this system in conjunction with other alternate light sources, says Tim Sleigh, a certified crime scene specialist and physical evidence/fingerprint expert and a sergeant with the RCMP Forensic Identification Services, E Division.

Because it has long worked with a large, room-sized laser, the RCMP was very aware of the detection advantages lasers brought to the table, says Sleigh. When a portable version became available, it weighed the advantages — improved evidence detection, reduced/better use of investigative time, less exposure to harmful chemicals, minimized need to interact with evidence — and decided to add the system to the agency.

Regarding lasers

Sleigh says this system has allowed his group to uncover evidence that traditional light sources have missed, and provides the following examples:

  • A CA-dye print on a firearm was soft and the clarity was poor (using UV ALS). But under the laser, and with no further treatment, the print clarity was strong. Further detail was revealed, leading to the identification of a suspect.
  • The laser revealed blood spatter pattern from under the cleaned, renovated and repainted drywall wall. Standard ALS did not show anything.
  • Writing in felt pen was exposed through fresh paint on a repainted scene wall.
  • The laser-detected ink residue and original signature were discovered on a social insurance card which had been buried and excavated at a scene. Standard UV light sources do not show this.
  • An undeveloped fingerprint has been revealed on paper, cardboard and painted wall, without the use of any developing medium. Another print is still visible after three years.
  • The written text of a letter was visible through a sealed envelope. The laser also detected some of the chemical components that would be found in a biological letter bomb. Standard UV lights do not have adequate intensity to enable this kind of identification.

"[The portable laser] discloses areas of disturbance in scenes to better facilitate or concentrate the search," Sleigh continues. "This results in more efficient human and time resource use and limits the total areas of destructive examination, reducing civil expenses."

Portable lasers should not replace standard alternate light sources but be considered another tool in the toolbox and "used in sequence with existing tools," says Sleigh.

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