FORT LAUDERDALE, Fla. -

A Broward County judge reduced the prison sentence Thursday for the now 23 year old who was convicted for his involvement in the fatal beating of a homeless man when he was a teenager.

Thomas Daugherty, 23, was sentenced to life in prison for his role in the death of Norris Gaynor, 45, in 2008.

Police said Daugherty was with Brian Hooks and Williams Ammons on the night in January 2006 in Fort Lauderdale when they beat up three homeless men. Gaynor, one of the victims, died from his wounds.

Since Daugherty was sentenced, the U.S. Supreme Court ruled that immaturity and failure to understand risks and consequences must be determined before a juvenile can be imprisoned for life. Daugherty was 17 at the time.

On Thursday, the defense argued for 20 years in prison while prosecutors asked for 40.

Daugherty took the stand in his own defense and made a tearful apology.

"I apologize to you for the pain that I know that I caused you," said Daugherty. "I want a second chance. I want to prove to everybody that I can do this."

One of the attacks was captured on surveillance video and made national headlines.

"I hate everything about that person. I don't remember that video. I don't remember doing that," said Daugherty.

Defense attorneys told the judge overseeing the re-sentencing that Daugherty was shuttled back and froth between a drug addicted mother and a physically abusive stepmother. Daugherty's parents, Bridgette and Thomas, also took the stand Thursday.

"Tom's life with me was like being at an all-night liquor store. The door was always open to whoever and whatever wanted to come into my home. Drugs were easily accessible, and if they weren't, then they were only a phone call away," said Bridgette Daugherty. "That is Thomas on drugs. That is Thomas on alcohol. That is Thomas on Xanax. It was Thomas on all the drugs that I provided to him."

"Did she, yes, verbally abuse Tom and physically abuse Tom? Yes she did. Soon as we found this out -- 'I'm sorry, it's not working out Debbie. Go.' But there is one lasting statement she made when she walked out that door: 'If you don't get this situation under control, if you don't get his mom under control, he's going to end up flunking out of school and going to jail," said Thomas Daugherty.

A doctor also testified, saying Daugherty suffered from depression and drug use.

Simone Manning-Moon, Gaynor's sister, seemed to be moved by Daugherty's honesty.

"He needs a chance at life. So did Norris. He is too young for this. So was Norris," said Manning-Moon. "A sentence of life is so very, very harsh. and so was the sentence of death for Norris. Can some mercy please be shown. Where was Norris' mercy that night?"

Hooks and Daugherty were convicted of second-degree murder in the attack on Gaynor and second-degree attempted murder in the other two beatings.

Ammons, who admitted that he shot the homeless man with a paintball gun, also faced life in prison, but he struck a deal with prosecutors to testify against Hooks and Daugherty in exchange for a lighter prison sentence.

Hooks received a 30 year prison sentence for his role in the crime. Ammons received a 15 years sentence.