"Buster was a good boy. He loved to have his belly rubbed," said Buster's owner, who did not want to identify himself out of safety concerns.

He said his family had just gotten home from his daughter's soccer game on Saturday evening, finding police at their Haslet home on Coyote Trail.

"Police were everywhere, Animal Control was here, and when I exited the car, they asked if I owned the dog, and I said yes, and then they told me my dog was murdered," Buster's owner said as he fought back tears.

He said it was the first time Buster and his other dogs had gotten loose from the backyard.

"My kids are tormented every day, every day," said Buster's owner. "They didn't understand why it happened. But I just keep telling them to understand that Buster's in another place... He's up there protecting our God."

Fort Worth Police said the neighbor who shot Buster said the American Stafford Pitbull was being aggressive towards him.

Over the phone, he told NBC 5 that when he initially came upon Buster, the dog was coming at him barking, and he thought he was in serious danger.

He said eventually the dog backed off enough so he could go back home.

The man said he didn't plan to come back, but his neighbor asked for his help looking for his Yorkie.

He said when they realized the neighbor's dog wasn't there, they turned around, and Buster "charged and attacked."

"I unfortunately had to take action, which I am upset about," he told NBC 5.

He said at the time, he didn't know whose dog it was: The neighbor he shares a backyard with.

He also didn't want to reveal his identity, fearing for his safety. He said he and his wife have been facing a lot of threats since neighbors started posting about the incident on social media.

He expressed his condolences to Buster's family.

"I was just trying to defend someone from imminent bodily harm, and I am very heartbroken that someone has lost their family pet," he said.

The man said he also fears for his job-- he works at Fort Worth ISD. The district said they are aware of the incident and have placed him on administrative leave pending the investigation.

NBC 5 spoke to other neighbors who said they didn't think Buster was aggressive when they came across him.

Cory Dawson said his family had just pulled into their garage and set their infant's car seat on the ground.

"I looked behind and a pit bull and another little dog were running up on us, so I hurried and grabbed my two-week-old daughter and we kind of separated ourselves," he said.

Dawson said they hadn't had any issues with Buster in the past, but were taking precautions.

"They weren't real aggressive but they were barking, so we just wanted to get out of there so we just shut the garage," he said.

He said he didn't know if Buster got aggressive toward anyone else.

Another neighbor showed NBC 5 security camera footage of the incident but did not want to release it.

It shows what appears to be the shooter and his neighbor standing near Buster's home. They are looking away from the home and appear to be talking when Buster comes toward them. The man aims his gun at the dog as the dog bounces around, at one point leaping up. The man shoots and Buster runs off-screen, toward his home. Another woman pulls up in her car and appears to yell at the two men.

"Buster-- died in my yard. Right there. Right there. At home. That's tough," said his owner, pointing to a flower pot in his front yard, near Buster's fence.

He said his family plans to have a memorial for Buster soon.

"My biggest prayer is that the world will pray for the man that shot my dog's heart to come to God. Because I serve a good God, and I'm going to stand on my faith," he said.