Neil Entwistle - For sale: the story of my wife's murder

A British computer worker who concealed massive debts and a fascination with casual sex behind a facade of domestic harmony murdered his American wife and their baby daughter before fleeing to the UK with the apparent intent of selling his story "to the highest bidder", a US court heard yesterday.

Neil Entwistle, 29, is claimed by prosecutors to have trawled websites for information about escort services and "adult friends", as well as instructions on how to kill with a knife shortly before he shot dead his 27-year-old wife, Rachel, and their nine-month-old child, Lillian Rose, at their rented home in New England on 20 January 2006.

The double murder took place just as it seemed the Entwistles, who met while studying at York University, were looking forward to a bright future after the birth of their daughter.

Ten days before the killings the family had moved into their leased detached house in the quiet suburb of Hopkinton, near Boston in Massachusetts. The large weather-boarded property was close to the home of Rachel's parents.

The jury at the Middlesex County Superior Court in Woburn, Massachusetts, heard allegations yesterday that Mr Entwistle led an increasingly desperate double life as he struggled to find work in the United States and his attempts to set up internet-based business ventures foundered, while also pursuing attempts to seek what he called "a bit more fun in the bedroom" with women he met online.

Michael Fabbri, the assistant district attorney leading the prosecution, said that within hours of the killings, Mr Entwistle drove his BMW to Boston airport and bought a one-way ticket to London before travelling to his parents' home in Worksop, Nottinghamshire.

When he was arrested on 9 February at Royal Oak Tube station in London he was carrying a notebook in which he had written how much he loved his wife and daughter. On the other side of the same piece of paper, the former IT worker had described "how he wants to sell his story to the highest bidder", Mr Fabbri said.

The prosecutor added that in the month before the murders, Mr Entwistle visited the Adult Friend Finder website "a number of times and began exchanging emails with females and discussing the possibility of setting up discreet relationships". At the time of his arrest he was also carrying a newspaper page containing a list of escort agencies and telephone numbers.

Mr Entwistle denies two charges of murder. He was also charged with possessing a firearm without a licence and possessing a firearm without a federal ID card.

His parents, Yvonne and Cliff, who were in court for the opening statements along with the family of Mrs Entwistle, have said they believe their son is "100 per cent innocent". Massachusetts does not have the death penalty and if found guilty the Briton faces life imprisonment without the possibility of parole.

The trial has already provoked controversy in America after his lawyers claimed that apparent prejudice among potential jurors showed he could not obtain a fair trial. The murder of his wife and daughter, who were shot in the head and stomach respectively, as well as his subsequent disappearance to the UK, generated widespread publicity in the US media about Mr Entwistle's lifestyle.

During the process to select a 12-strong jury from a panel of 189 people, one potential juror said: "I think he's guilty and I'm unlikely to change my opinion." Another woman told the court she had heard other jurors say: "Fry him, send him away." An attempt by his defence lawyers this week to have the case dismissed or moved to a different location was dismissed by the trial judge, Diane Kottmeyer, who said the selected jury had demonstrated its impartiality.

Mr Fabbri said that outwardly the Entwistles, who were both adept at using computers, had seemed "nothing but loving and stable". But he said there was "another side" to Mr Entwistle, who feared his debts and active pursuit of an adulterous relationship would be discovered by his wife.

This ruthlessness was allegedly demonstrated by his response when he claimed to have returned from a two-hour shopping trip to a branch of the stationery chain Staples to find Rachel and Lillian Rose curled up together in the main bedroom, already dead from their wounds.

In a police interview, Mr Entwistle said: "I didn't even call 911 or call for help. It was obvious what had happened. I could see the hole in Lilly. After I came and found them in the bed I covered them up. It was like I was closing them off. My first thought was to go downstairs and get a knife from the kitchen to hurt myself, but I knew that would hurt so then I decided to get in my car and leave the Hopkinton home."

The court heard that DNA evidence would be presented linking Mr Entwistle to the grip of the handgun used for the murders, as well as an ammunition container. The weapon was a .22 revolver belonging to Mr Entwistle's father-in-law, Joseph Materazzo, which it is alleged the IT worker took on the day of the killing by using a spare set of keys to enter his in-laws' house.

Lawyers for Mr Entwistle said his actions after the killings were consistent with those of a grief-stricken husband and father and that evidence would be brought to show his innocence. Elliot Weinstein, for the defence, said: "Everything he said and everything he did thereafter he did because he loved them, he did because he loved them both."

The trial continues.