Atticus, a brown and white Australian shepherd, was taken by a young male after the shelter denied him an adoption, according to the SPCA.
The suspect, who was accompanied by two friends, took the puppy and disappeared, shelter officials said.
Staff members had the suspect's last name and address. They used Facebook to identify him and gave the information to the Santa Cruz County Sheriff's Office. He lives in Monterey County, and Monterey police and the Monterey SPCA were brought in to help, shelter officials said.
Monterey SPCA officials found Atticus at the suspect's apartment.
The puppy was safe and is back at the shelter waiting to be adopted into a good home, shelter officials said.