A Georgia investigation into a school officer charged with cruelty when his dog died in a hot patrol car has widened after he admitted shooting a second dog and the authorities discovered the carcass of a third animal, officials said on Wednesday.

Investigators said two of the dogs had been K-9 partners of the veteran officer, Lt. Daniel Peabody, 50, of Cherokee County. Aside from raising questions of animal cruelty, the case also threatened the public trust, an official said, since it involved the actions of a school law enforcement official.

The lieutenant has since resigned.

Last month, Lieutenant Peabody left the dog he worked with, a Belgian Malinois named Inca, in a hot, unventilated patrol car parked at his home about 4 p.m., county marshals said in a statement. The car was not equipped with a kennel or an alarm system for high temperatures, said Maj. Jamie S. Gianfala, a spokesman for the marshals.