JACKSONVILLE, Fla. -

Prosecutors presented more evidence and put their star witness on the stand Thursday afternoon in the trial of a man accused of burying a Jacksonville couple alive.

Michael James Jackson is one of four people accused of killing Carol and Reggie Sumner, who were kidnapped from their home and killed in July of 2005.

Police said the couple was buried alive in Georgia.

Since the start of Jackson's trial, the jury has been hearing audiotapes of Jackson talking about the crime.

The prosecution on Thursday presented a videotape showing Jackson in an interview they said he had requested with Jacksonville Sheriff's Office detectives.

The tape begins with Jackson alone in the room, talking, singing and laughing to himself. When detectives entered the room, the almost hourlong recording starts with Jackson repeatedly asking what he could do for a lesser sentence.

"Plan and simple ? what do I got to do, what do I got say? Point this, this and this," Jackson was heard saying in the interview.

After the detectives told him he could do nothing to lighten his sentence, Jackson began blaming his girlfriend, Tiffany Cole.

"That's when she started telling me about how much money these people had," Jackson said.

The prosecution also played an audiotape of a phone call Jackson made to his grandmother from jail.

"You're in the newspaper, all over the newspaper yesterday and today. For what -- murder," Jackson's grandmother said during the phone call.

Also on Thursday, the prosecution put Bruce Nixon on the stand, calling him a co-conspirator in the Sumner's deaths.

Earlier this year Nixon pleaded guilty to two counts of second-degree murder, armed kidnapping and armed robbery.

Detectives said Nixon was the man who led them to the grave.

On the stand, Nixon said Jackson did all of the things he is accused of and was the mastermind behind the crimes.

"Mr. Sumner was sitting in the chair and Mrs. Sumner was crying on the couch," Nixon said on the stand.

He said the woman had been crying and asking not to be hurt.

Nixon testified that Jackson told he another man, Allen Wade, to put the couple in the trunk.

"What were the Sumners doing when you popped the trunk and duct tape came off?" the prosecutor asked Nixon.

"They were hugged to each other," Nixon replied.