Lighting the Laser Lens

Evidence collection has benefited greatly from lasers. They can be used for trajectory analysis, measurement and evidence collection in and out of the lab. Because of their high intensity light beam compared to alternate light sources (ALS), lasers also are capable of uncovering evidence often missed by other ALS and are able to show evidence in greater detail and clarity — without spraying or special treatment.

However, until now, lasers were confined to the lab, being too large and unwieldy to transport to crime scenes. This lack of mobility required that evidence be identified and captured in the field and then taken to labs for further analysis.

Reconstruction

Reconstructive trajectory analysis inspired the need for a ballistic laser for in-field investigations.

Previously, trajectory analysis had short-distance limitations by using tools such as probes, dowels, strings and the traditional red laser. These tools accompanied many difficulties such as drooping, sagging and bending — potentially creating inaccurate data for lab and court reconstruction. Additionally, the traditional laser could only show the terminal points and was difficult to visualize in less-than-ideal conditions without fogging agents or smoke — not to mention the complications to photograph the beam.

The CAO Group Inc., located in West Jordan, Utah, developed the Vector-BLS ballistic laser to combat these difficulties for indoor and outdoor trajectory reconstruction. The Vector, according to Professor Tim Palmbach at University of New Haven, Connecticut, "has the ability to display a bullet trajectory with tremendous brightness, thus making visualization and photographic documentation much simpler."

The Vector system operates from built-in 12-volt rechargeable batteries powering an adjustable beam range output of 0.1 to 300 milliwatts at 532 nanometers (nm). It is six times bright and has 100 times the power output of standard red lasers. Additionally, the laser may be operated while attached to an external power supply such as a vehicle or generator.

Important features of the Vector-BLS system include:

  • A range of 1,000 yards to display both trajectory and terminal points.
  • A tripod to increase stability on solid surfaces.
  • Two leveling bubbles and adjustable screws for accurate data on slopes and uneven ground.
  • A remote interlock switch to add distance between users and the laser.
  • Separate horizontal and vertical buttons for complete angle control.
  • Optional shut-off timer if desired — Vector will never shut off on its own.
  • Saved vertical ranges of either 360 degrees or 400 gradians.
  • Adjustable sighting scope to locate a distant point or target with dust cap.

A control panel display shows either all or current data selected. The upper control display indicates both the vertical and horizontal angles, based on predetermined zero-points. The controls allow users to choose between three different vertical modes:

  1. Zenith angle: Zero degrees is straight up; parallel with the horizon is 90 degrees, and straight down is 180 degrees.
  2. Vertical angle: Zero degrees is parallel with the horizon; straight up is 90 degrees, and straight down is displayed as 270 degrees.
  3. Height angle: Zero degrees is parallel with the horizon; straight up is displayed as positive 90 degrees, and straight down is displayed as negative 90 degrees.

Ballistic laser-gathered data not only assists investigators and officers in the field and labs, but in the courts as well.

"The courts will be able to visualize the proposed trajectory better," says Palmbach. "Officers will be able to give them actual hard data related to the vertical and horizontal aspects of the trajectory. Not only will it get much more objective, it will give opposing experts a better opportunity to evaluate each others work product and opinions derived from that analysis. Ultimately this increases creditability in the field of shooting reconstruction."

Revealing

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.

"I cannot overstress that standard ALSs are harmful to DNA deposits/stains in the UV spectrum and can be highly destructive to DNA," he adds. "The laser is specific to the green side of the spectrum and less harmful, offering investigators more latitude in a scene. As well, new laser technology does not generate the heat at the optic end of the process. This also is less harmful to DNA as well as to fingerprints."

Law enforcement agencies have been very open to this technology, not only for the improved evidence detection, but also because of reduced risk to evidence and personnel, says Kauf. UV lights require investigators to spray, sometimes very widespread areas, and this can harm DNA and is not always healthy for people, he explains. Lasers do not require spraying, saving material, time and money.

"The biggest obstacle is funding and getting the funds for this new technology," he says. "Most agencies work on very tight budgets."

But, asks Kauf, who can afford to overlook more evidence? Or jeopardize a case?

"You want to apply the latest technology to find evidence, and the latest technology is laser technology," he says. "If you go before a judge and the judge asks, 'Did you use the latest technology?' and you say, 'No,' you have already weakened your case."

Pamela Mills-Senn is a freelance writer based in Long Beach, California. She specializes in writing about public safety issues.

Loading