Exclusive: Aaron Vargas Regrets Killing Alleged Abuser

May 21, 2010— -- Aaron Vargas, a young father who fatally shot his former neighbor and claimed he had been sexually abused by him, said he regrets killing Darrell McNeill.

"I'm still trying to make sense of the situation," Vargas told "20/20's" Chris Cuomo in an exclusive interview. "It's not up to me to decide someone's fate."

On a February 2009 night in Fort Bragg, California, Vargas visited McNeill's trailer and killed him with a single shot to the stomach. But Vargas told Cuomo that killing the 63-year-old man was the last thing he ever wanted to happen.

"I didn't go to there to shoot the guy. I went there to warn him off," Vargas, 32, said. "He [McNeill] needed to stop. That's for sure. He didn't need to be shot and killed. But he needed to be stopped."

Within hours of the shooting, Mendocino County sheriff's investigators arrested Vargas and indicted him for first-degree murder. Vargas pleaded guilty to voluntary manslaughter in March and is expected to be sentenced next month. He is facing up to 10 years in jail.

Vargas said he doesn't belong behind bars.

"If the law doesn't work, ... it doesn't work," Vargas told Cuomo, adding that police had "plenty of chances" to arrest McNeill.

After the incident, Vargas' family said several men in their 30s and 40s came forward saying that they, too, had been abused by McNeill. One said they had warned the Fort Bragg Police but no action was taken.

"He [McNeill ] was actually damaging people and it wasn't a game anymore. You know? He played his whole life like it was a game," Vargas said. "He'd see that, finally, this wasn't going to keep going. And we weren't going to be little puppets anymore."