Question

several shell casings were found at the scene of a double homicide. can these be used in the forensic laboratory to determine who the perpetrator is? report an error question 3 of 5
yes. it is possible because the forensic scientist can analyze the casings and compare them to casings used in other crimes and recorded in a database.
yes, but only if there are fingerprints on them. the casings themselves wont help.
no. only the bullets taken out of human bodies can be used.
no. the forensic scientist has to have the gun that was used.

Explanation:

Forensic scientists can analyze shell - casings. Each gun leaves unique markings on shell - casings during firing. These markings can be compared to those in a database of casings from other crimes to potentially identify the gun used and thus the perpetrator. Fingerprints are not the only way shell - casings can be useful, and they are useful even without the actual gun or bullets from the victim's body.

Answer:

Yes. It is possible because the forensic scientist can analyze the casings and compare them to casings used in other crimes and recorded in a database.