ABC News' Alana Greenfogel reports:

The now released 911 call placed by a Santa Fe, N.M., man revealed his frantic horror when he returned home last week to find that the family dog had mauled his father, who lay dead on the front porch.

Gavin Wright, 27, made the difficult decision Tuesday to have his dog, Achilles, euthanized after he returned home May 2 to find his father dead, having bled to death after being attacked by the dog.

"My dad is dead on the front porch. It looks like my dog got a hold of him," Wright told the 911 dispatcher.

He became more emotional as he attempted to describe the horror at the scene over the phone.

"My dad is f***ed up," he said, becoming more agitated. "Did you not hear me? My [expletive] dad is dead. … I don't think you understand, I can't help him. You don't understand, the wounds I'm talking about. He bled to death."

Wright, who lived with and took care of father Clifford, 74, told the dispatcher that he had just returned home from work when he discovered what had happened.

The American pit bull terrier was once a beloved household pet and member of the family who, for reasons Wright doesn't understand, became a vicious killer. He said the dog and his father were close.

"Today was just a decision day for the dog," he told ABC News Tuesday. "That's one of those decisions where you're pinned in a corner."

Achilles, 4, had been with the Wright family since he was a few weeks old.

Wright says he went to say goodbye to Achilles at the shelter Tuesday, adding that the jumped up, tail wagging. Although he wanted to fight to get the dog back, he is now fighting to move on with his life. If he had not surrendered the dog to be euthanized, he could have faced citations for having a violent animal.

"Him knowing exactly how his father died, and what pain he endured during this attack, that was literally the final chapter," Santa Fe police Lt. Louis Carlos said of Wright's ultimate decision to let the city kill Achilles Tuesday afternoon.