
Fierro had adopted the dog from a pet rescue organization that took it in after it was removed from an abusive home.
He could have called the organization at any time if he was having trouble with the dog, and they would have gladly taken it back, the group's founder said on Friday.
"It's so unfortunate how this ended up," Lisa Klotnia of the Chicago Canine Rescue Foundation said. "This guy could have called us at any time to help him out."
Instead, Fierro, of the 500 block of West Roscoe Street is charged with aggravated animal cruelty, police said.
About 3 a.m. Friday, Chicago Police received a call from a man saying he had been angry when he killed his dog and placed it in the trunk of his car, News Affairs Officer Laura Kubiak said.