The Ballistics Unit (BU) assists investigators in processing crime scenes and
analyzing evidence in cases that involve the use of firearms. Ballistics Unit
investigators identify types of weapons and ammunition, conduct microscopic
comparisons of bullets and discharged cartridge casings recovered at crime
scenes, hospitals or morgues. Test firing weapons for operability, examination
of projectiles and the identification of tool marks and gunpowder residue are
core functions of this Unit.

The Unit houses the state-of-the-art Integrated Ballistics Identification
System (IBIS) computer search system, an image analyzing system for
acquiring, storing and comparing the images of bullets and cartridge cases.
The IBIS system captures video images of striations on bullets and tool
marks left on cartridge cases, which are used to produce an electronic
signature. These are compared with images stored in a local database, and
a list of possible matches are assigned numerical scores, the highest of
which are chosen and viewed under a comparison microscope for
possible links between cases. In addition, if investigative information
warrants, the ability to search databases state and nation wide exists, thus
revolutionizing the way ballistics evidence is compared and connected.

The BU processed a total of 371 cases involving the use of firearms. In 2005,
a total of 304 firearms were examined and tested. Ballistics personnel also
conducted 24 lectures and seminars at the Westchester County Police
Academy, local colleges and high schools. In addition, the BU offered expert
testimony in 41 different trials in Westchester County and Supreme Courts,
as well as in the Federal Southern and Eastern District Courts.