A British man accused of killing his wife and infant daughter in their Massachusetts home and then fleeing the country pleaded not guilty Tuesday to murder.

Neil Entwistle, 27, is charged with two counts of murder and firearms charges in the Jan. 20 slayings of his wife, Rachel, 27, and their daughter, Lillian Rose, who would have turned 1 on Sunday.

Prosecutors also released new details Tuesday about troubles in the Entwistles' marriage and inconsistencies in stories that Neil Entwistle told about the killings.

According to documents filed by prosecutors, Entwistle's computer records showed an exchange of e-mails with a woman he found through a Web site called "Adult Friend Finder." He told the woman he was in a relationship "but looking for a bit more fun in the bedroom" and "a very discreet relationship just for fun."

Prosecutors have said Entwistle shot his wife and daughter after racking up tens of thousands of dollars in debts that his wife apparently didn't know about.

Entwistle allegedly told a state police detective that he found the bodies of his wife and daughter when he returned to the Hopkinton home they had rented after running errands. He said he drove 50 miles to his father-in-law's house to get a gun so he could kill himself but couldn't get inside the house and decided to go home to England to be with his parents.

In England, Entwistle told friends a different story, according to a summary filed by prosecutors Tuesday.

Entwistle allegedly said he drove to his mother-in-law's work place, told her he had found the bodies, and then gathered with his wife's family in Carver to "mourn the news." He said he "began to feel left out" and went straight to his parents' home in Worksop, England, according to the summary.

Prosecutors said they have evidence that Entwistle rented a car when arrived in England, spent a night in a hotel and drove almost 800 miles before going to his parents' home.

According to investigators, Entwistle had also done research online about ways to kill people and how to commit suicide. Investigators say he may have planned a murder-suicide but couldn't go through with it after killing his wife and daughter.

In court Tuesday, he stood silent as his lawyer asked the judge to enter a not guilty plea to all counts, including murder and weapons charges.

Rachel Entwistle's mother and stepfather, Priscilla and Joseph Matterazzo, and about a dozen friends and family members watched the short proceedings.

"They miss Rachel and Lillian Rose every minute of every day," said family spokesman Joseph Flaherty. "It doesn't bring them any comfort to see him standing there and know that their daughter and granddaughter are gone."

Superior Court Judge Peter Lauriat set a goal of starting the trial by April 2007. If convicted, he faces a mandatory life sentence; Massachusetts does not have a death penalty.