Who Killed Terry King?

A 13-year-old boy took the witness stand Wednesday and calmly denied that he and his brother killed their father with a baseball bat last fall.

Alex King's testimony came only a few hours after prosecutors played a tape-recorded statement in which he confessed to police. But Alex, with choirboy looks and undersize for his age, told jurors that a family friend he had once loved emotionally and sexually committed the murder.

"He told us that there had been a fight," Alex testified. "He said he had killed my dad to protect us."

Alex gave similar testimony against the man, Ricky Chavis, at Chavis' trial last week. Chavis, 40, was tried for the same crime before a different jury, but the verdict will remain sealed until the boys' trial is over.

Like Chavis, Alex and Derek King are being tried as adults on charges of first-degree murder and arson. Each would receive an automatic sentence of life in prison without parole if convicted of killing Terry King, 40.

The boys' mother, Kelly Marino, is from Lexington, Ky.

The boys were 12 and 13 at the time of the slaying.

For the second time in as many weeks, Alex repudiated confessions he and Derek, now 14, gave to Escambia County sheriff's deputies a day after their father was bludgeoned to death.

Alex said the brothers hid in the trunk of Chavis' car while Chavis killed their father shortly after the boys returned home from running away. They had spent nearly 10 days with Chavis, hiding under a trap door when their father came to visit, Alex said.

Firefighters found King's body inside his burning home Nov. 26.

Unlike last week, when he testified in a green jail jump suit and handcuffs, Alex had on a long-sleeve dress shirt and tie and his hands were free. He looked straight at the lawyers as he answered their questions instead of staring down most of the time as he had done last week.

He testified that Chavis committed the murder because he was afraid Terry King would find out he was having sex with the boy. Chavis persuaded the brothers to take the blame by telling them that, as juveniles, they could get off by claiming self-defense, Alex said.

"I wanted to be with Rick because I was in love with Rick," the boy said. "He said my dad would have killed us before he would have let us go."

Alex said Chavis let the boys play video games, watch television as late as they wanted to and smoke marijuana at his Pensacola home.

Earlier Wednesday, prosecutors played the boys' tape-recorded confessions to police. In those statements, Derek admitted killing his father while Alex said it was his idea, claiming the brothers were afraid of being punished for running away.

The first blow of the aluminum bat sounded "about like wood cracking or hitting concrete or something," Alex said in his statement.

Sheriff's investigator John Sanderson testified that both boys initially claimed Derek had struck their father during a struggle. Derek had given his statement first.

"I told him that based on the crime scene — the crime scene tells the story — we know what his father was doing, where his father was at," Sanderson testified. "At that time he changed his story."

Sanderson said both boys then said they had waited until their father was asleep before he was bludgeoned.

The prosecution wrapped up its case Wednesday and the defense is scheduled to continue making its case Thursday. Chavis still faces trial on a single count of committing a lewd and lascivious act against Alex.

CBSNews.com Legal Analyst Andrew Cohen had this take on the strange two-trial prosecution:

"It's not unusual to have co-defendants to a murder. What's unusual is to have separate trials in which the government's theories of the case contradict each other. Either the boys did it or Chavis did but all three could not have done it if you buy the prosecution's argument and that means big problems for the State on appeal if there are convictions in both cases", writes Cohen.

"The boys' credibility is the whole case. First they confessed to the crime and then they recanted in a way that led prosecutors to indict and try Chavis for the same crime. If the jury believes the boy's initial story, they are as good as convicted.

"Prosecutors cannot be right in both cases - either the boys killed their father or Chavis did - which means that in one of these cases prosecutors will stand up in front of a jury and unjustly accuse and try to convict the wrong person or people," Cohen concludes.