Duffy-Stephenson had gone with her family to a wedding in Florida. Duffy-Stephenson returned to go back to work as teacher's aide for autistic students at Archie R. Cole Junior High School in East Greenwich while her family stayed in Florida. Her husband, James O. Stephenson III, and their then 3-year-old son remained in Florida.

She went to a teachers' union dinner on Nov. 16 but then missed two following days of work.

In his opening statement, prosecutor William Ferland cited a number for the jury: 99.9993462

That, he said, is the percentage of the population that did not have the DNA that was in a sample collected from under Duffy-Stephenson's fingernails. But a DNA expert, he added, could not exclude Richardson from having that DNA.

"In every way, the defendant's DNA is consistent" with the DNA found under her fingernails, Ferland said.

During the prosecution's opening, jurors saw a picture of Duffy-Stephenson projected on a screen.

But in his opening statement, defense lawyer John Hardiman countered with Richardson's alibi that he had been home at the time Duffy-Stephenson was slain and that a number of family members could attest to that. Hardiman detailed what Duffy-Stephenson was doing during the time authorities accused him of killing Duffy-Stephenson

Hardiman also sought to lessen the significance of the prosecution's DNA argument, saying there was other people's DNA on other things in the room, such as a safe from which money had been taken.

The police have said they found a basement office that had been rummaged through in the Cowesett area home. The safe that had contained $11,000 was found empty, they said. The office was home to Picture Perfect Landscaping, Duffy-Stephenson's husband's business.

Richarson was arrested in December 2005, after the police said they found his DNA beneath Duffy-Stephenson's fingernails. He was indicted in March 2006 on murder and burglary charges, and remains at the Adult Correctional Institutions.

Richardson, 40, began working for Stephenson in 2000, shortly after he was paroled from a Connecticut prison, and worked for the business for more than four years. In 1996, Richardson was convicted of kidnapping a female hitchhiker in Lebanon, Conn., binding and gagging her with her own clothes and beating her.