PATERSON - The former owner of a dog responsible for killing a 13-year-old boy says she never knew the bull mastiff known as "Trigger" to be violent, but that his limits must have been tested.

Kenneth Santillan was found dead Friday near a creek in Paterson. The attack shocked the family who say they gave the dog to its current owner Paul Clarke three years ago.

"He was playful, loving, he was very protective," says Gina Falcon. She says her niece and nephew would drag him by the tail, something she'd warn them against. "But he just wouldn't care, he would just play," she says.

The 115-pound dog escaped its backyard fence and went after two 13-year-old boys. Santillan was found dead along a brook behind Clarke's house. His classmate escaped with bite wounds on his arm. 

It's not clear what led to the attack, but a neighbor says school kids often taunted Trigger, who was kept outdoors.

"The dog was always in the backyard minding its business," says Edward Clarke. "Of course, kids, they come along and try to test the limits. And that's what they did and this is what happened."

Kenneth Santillan's father told News 12 New Jersey the family is still making funeral plans for their son.

Trigger was euthanized following the attack. Rabies test results have not yet been released.