This article will discuss how equipment can influence the design and infrastructural needs of two laboratory space types where the identification of evidence takes place. We will discuss an ALS examination room and its key components and then move into the needs of specific latent print identification equipment.

The uses of alternate light sources (ALS) for the identification of such evidence as biologicals and latent prints are supported by properly designed rooms dedicated to their use. These light sources function by providing specific wavelengths of light that identify certain types of evidence better than standard spectrum visible light. Some of the features of a well designed ALS room include an overhead service carrier, forensic exam tables, room darkening measures, and considerations for the specific alternate light source or sources being used. Information regarding the advantages of each of these follows.

An overhead service carrier (OSC) is a device that can provide access to power, data, snorkel exhaust, exam lights, and other services. An OSC is particularly useful to the design of an ALS room since,mounted to the ceiling, they provide access to services without restricting the work area below. Forensic exam tables (FXTs) are often provided with lockable casters, height adjustment, a paper roll dispenser, attached storage, and accessories to facilitate examination of evidence. Since evidence can range from tall items that need to sit on the floor to items too long to fit on one table, the ability to combine multiple FXTs provides the flexibility to lay out examination space as needed. Additionally, since FXTs provide storage and paper roll dispensing within the unit itself they supplant the need for these other amenities in what can otherwise often be a small room. ALS rooms are equipped with standard laboratory lighting for making a visual inspection and inventory of evidence but require darkening capabilities for proper use of the ALS. Blackout shades are commonly used for windows to achieve room darkening requirements while also giving an examiner the ability to use natural light when desired.As the room’s purpose is to provide a space to use an ALS, consideration should be given as to how alternative light sources are going to be used and mounted in the room. One option is to mount the ALS on the OSC. This keeps the ALS out of the way, but may introduce complications such as having to mount the ALS controls on an adjacentwall. An ALS could also be placed on a small cart formobility. Most are either battery powered or require a standard electrical outlet and are relatively light. For example, the Melles Griot Omniprint 1000A weights 18 pounds¹ while the Mini-CrimeScope 400 from SPEX Forensics is 15 pounds.² Thus manually moving an ALS from FXT to FXT is not prohibitive.

One particular type of alternate light source, a forensic laser, may have greater infrastructure requirements than other types of ALS. While some forensic lasers, such as Spectra Physics’s REVEAL lasers, only require a standard 120 volt outlet,³ other lasers, especially older lasers, may have special electrical needs and require a water chiller. Water chillers generally require a cold water supply as well as a floor drain in the room to capture any water that may spill from the chiller during routine maintenance or system failures. Lasers, based on OSHA requirements, also have safety requirements. OSHA requires that laser warning signs be posted at the entrance of the room where a laser is being used. Additional, more stringent requirements are necessary if the laser being used for examination is a Class I Vlaser. One example would be door interlocks where, in the event the door were opened while the laser was in operation, the laser would automatically shut off.⁴

Just as the equipment used in ALS spaces has special requirements that affect the design of the spaces it is used in, other equipment used in the discovery and development of latent prints also affects laboratory design and infrastructure.