Computer screen showing a side-by-side comparison of hammer marks on two ammunition casings. Nebraska State Patrol Crime Lab.

- Image ID: BKNFJ2
Computer screen showing a side-by-side comparison of hammer marks on two ammunition casings. Nebraska State Patrol Crime Lab.
Mikael Karlsson / Alamy Stock Photo
Image ID: BKNFJ2
Computer screen showing a side-by-side comparison of hammer marks on two ammunition casings. Nebraska State Patrol Crime Lab. By comparing casings side by side experts can determine if a casing found at a crime scene is fired from the same weapon as one found on a suspect.