Mr. Richardson, 33, was indicted on a felony animal-cruelty charge, prosecutors said Friday. If convicted, he faces up to two years in prison.

Image Onyx, the dog that was stabbed and killed, as a puppy. Credit... Bronx district attorney's office

“This is an incredibly vicious crime,” the Bronx district attorney, Darcel Clark, said in a statement. “Cruelty against animals will not be tolerated.”

According to the district attorney, Onyx’s owner stopped by Mr. Richardson’s apartment on Fulton Avenue in the Claremont Village neighborhood on the day of the killing to check up on Onyx as she often did, and found the 54-pound dog dead in the bathtub.

Around the same time, prosecutors said, someone in the building called 311 to report animal abuse. An officer, Anthony Alvino of the 42nd Precinct, was dispatched.

The criminal complaint condenses Mr. Richardson’s statement to the officer, “in sum and substance,” as follows:

“We went to the park and were playing. The dog bit me, I hit the dog a couple of times. The dog left and I walked back home. When I got home I saw the dog. I picked up the dog, put him in the bathtub and took him out of his misery.”