"Today I betrayed my best friend and put down my best friend," Santino wrote in a suicide note. "Rocco trusted me and I failed him. He didn't deserve this."

Santino, who was raised in an orphanage and foster homes, adopted Rocco from a shelter several years ago, and wrote fondly of his dog on his Facebook page, saying "I did not rescue Rocco, Rocco rescued me."

But, in 2010, Santino began to have issues with residents in his building, after new strict dog regulations were announced, which included a ban on pit bulls.

Although the ban didn't affect residents who already had pit bulls in the building, many of Santino's neighbors reportedly weren't fond of Rocco, and complained often about the dog, which wasn't allowed to be left in Santino's apartment alone for more than nine hours or ride in the main elevators.