Are Your Eyes Ready to Search a Crime Scene?


Locating fluorescent evidence at a crime scene doesn’t just require a good ALS and goggles; it also relies on the perception of the investigator. But on entering a darkened crime scene we’re likely to miss evidence unless we allow time for our eyes to adapt. How long does dark adaptation take and how do we know when we’ve achieved it?

The Crime-lite Eye is a simple hand-held device that allows investigators to check…

Human vision has a remarkable ability to cope with both very bright and very dark conditions. In response to darkness, our eyes will make some rapid adjustment to achieve a first level of night vision, but given more time they can become up to a million times more sensitive. This can have important implications for evidence searching since we won’t achieve the best or consistent results unless we allow sufficient adaptation time.

The amount of time needed for dark adaptation will vary for each individual, and can be affected by factors such as the previous lighting environment. In some cases it can take 20 minutes or more.

To help investigators and agencies establish a standard protocol, Foster & Freeman have developed the Crime-lite Eye. This low-cost, easy to use device has an LED display showing the numbers 1-20 at varying degrees of illumination intensity.

The examiner selects the desired sensitivity level (1-20) and then, upon entering the dark environment, waits until the chosen sensitivity level is reached. Once the selected level becomes visible, darkness adaptation has been achieved and crime scene searching can begin.


Find out more about the Crime-lite Eye