A gang suffocated a Bermudian woman to death while they bludgeoned her husband with a stereo speaker.

Chief Assistant District Attorney Alonza Whitaker revealed the causes of death of Sherlene Robinson and Jerry Church as he reflected on their double homicide yesterday.

On Friday, Dereck Cox, 19, and Kevin Thomas McKay, 22, pleaded guilty at a pre-trial hearing to murder, robbery, burglary and theft. They were each sentenced to life, plus 20 years for Cox and 40 years for McKay.

Richard Strickland, 17, and Gage Bryant, 14, admitted robbery and burglary. Charges of murder and aggravated assault and battery were dropped but each was jailed for 20 years. Strickland also received 20 years' probation while Bryant received 15.

"This was a shocking crime, and the most shocking part was the age of the participants," said Mr. Whitaker. "The youngest one was 13 at the time and the oldest was 21."

Ms Robinson, 57, and Mr. Church, 61, were killed at their home in Waverly Hall, Georgia, US, last June 28. Their bodies were only discovered two days later, after police arrested McKay for crashing their car while under the influence.

Officers arrived at the house to inform Mr. Church of his stolen Chrysler Sebring but found blood on the screen door and a body on the floor. Another body was then discovered in the living room.

Mr. Whitaker said it was unknown why the gang targeted the couple but that two defendants lived in the same middle-class neighbourhood of Melody Lakes.

He said the motive was robbery the gang took the couple's cars and bank cards.

"This was a brutal killing. It was thought-out and planned, and then that plan carried out," said Mr. Whitaker.

"Mrs. Church died from asphyxiation while Mr. Church died from blunt force trauma, being beaten around the head and loss of blood."

Mr. Whitaker said Ms Robinson (Mrs. Church) may have been strangled, smothered, or held down by someone compressing her chest.

"As their bodies were not discovered until more than two days after their death, that did not leave the medical examiner with the best of opportunities, so we have used the legal term of asphyxiation, or suffocation," he said.

"We don't know exactly how, as each defendant is minimising their involvement."

Commenting on Mr. Church's death, he said: "There was evidence a knife was used and a stereo speaker. He had stab wounds to the throat and the speaker was used in blunt trauma to the head. He was also punched and kicked."

Mr. Whitaker said that as two defendants were juveniles at the time of the offence, only two Cox and McKay were eligible to face the death penalty. In Georgia this is administered by lethal injection.

To proceed down this route however, would have meant holding separate trials for all four defendants. Mr. Whitaker said that due to the defendants blaming each other, it was hard to pin down who was most responsible for the acts of violence.

"As the death penalty is the ultimate sentence, juries want to make sure they have the right person," he said.

"Each one probably had a part in it but the question was, which one was the most culpable?"

Mr. Whitaker said the youngest, Bryant, stood outside as a lookout.

"In this case we had three people in the house but each one is pointing the finger at the other."

He added: "We determined that although the case was one which was worthy of the death penalty, it was one we may not have been successful in, so we took another route which was life for the two adults."

The four defendants were due to face joint trial on February 23. However, last week during pre-trial motions to determine admissibility of evidence, a plea agreement was reached at Harris County Superior Court.

"The families of both victims are relieved," said Mr. Whitaker. "Usually a case like this will take up to a year-and-a-half to reach trial, so they are pleased it is now behind them."

He said Strickland and Bryant both apologised to relatives, with Bryant reduced to tears on being shown photographs of the victims. "It really caused him to reflect on what he had been a part of," said Mr. Whitaker.

"We are pleased we won't have to put the family through a trial. Hopefully this will now start the healing process and allow them to move on."