FLORENCE — Shannon Ray Johnson refused to testify today against his brother, Alfred Shawn Johnson, in Shawn Johnson’s murder trial.

Shawn Johnson, 42, is charged in the 2000 death of Keith Barnett. Barnett was found beaten and unconscious on Alabama 17 in Lauderdale County on July 29, 2000, and died Sept. 21, 2000.

The brothers are charged with killing Barnett, 22, by beating him with a baseball bat. Shannon Johnson, 43, had agreed to plead to manslaughter and receive a 20-year prison sentence in exchange for his testimony, but said he changed his mind.

“I’m not going to send my brother to prison for the rest of his life for something he didn’t do,” Shannon Johnson said under cross-examination from Shawn Johnson’s defense attorney, Jamy Poss.

He said he and his brother are innocent, but he realizes he probably will spend the rest of his life in prison for refusing to go along with the plea agreement.

“So getting on the stand today...” Poss said.

“...is costing me the rest of my life,” Shannon Johnson replied.

Lauderdale County District Attorney Chris Connolly asked Shannon Johnson about testimony he made on Jan. 20, 2012, in which he stated he and his brother got in an altercation with Barnett outside Little Sands bar in Wayne County, Tenn. In that statement, Shannon Johnson said Shawn Johnson hit Barnett with a baseball bat and they put him in their pickup.

“I wasn’t telling the truth,” Shannon Johnson told Connolly.

Connolly said Shannon Johnson’s refusal to testify could impact the plea agreement.

“It’s under review,” Connolly said. “We’ll have to evaluate it and make a decision once we get through this trial.”

Testimony continues Thursday, with the prosecution likely calling its final witnesses, followed by the defense beginning to present its side.