Louise Mensch was in the USA when the email was sent

A Conservative MP was sent a threatening email telling her she would have to choose which one of her children would die, a court has heard.

Mother-of-three Louise Mensch, who is MP for Corby in Northamptonshire, was told she faced a "Sophie's Choice" - a reference to a novel and later film in which heroine Sophie has to choose between the life of her son or daughter at a Nazi concentration camp.

The sinister email was purportedly sent from the online hacking group Anonymous, Gloucester Magistrates' Court heard.

However, police later arrested and charged Frank Zimmerman - a 60-year-old agoraphobic living in a run-down house in Gloucester.

Zimmerman, of Spinney Road, Barnwood, Gloucester, was accused of an offence of sending by public communication network an offensive, indecent, obscene, menacing message or matter on 22 August last year.

The court heard that Zimmerman had failed to attend any court appearance to answer the single charge he faced or give proper instructions to his solicitor - blaming his agoraphobia and depression.

Defence solicitor Charles Cronin told District Judge Martin Brown that he had spoken to Zimmerman by telephone and that he would not be attending court and was instead going back to bed.

In the defendant's absence, Judge Brown decided to proceed without him and held a hearing to determine whether Zimmerman had committed the offence.

Prosecutor Gaon Hart told the court that that Zimmerman had sent the email to Mrs Mensch after she had spoken out publicly during last summer's riots calling for the police to be able to temporarily close down social network sites, such as Twitter and Facebook, if necessary.

Zimmerman originally made contact with the chick lit author-turned-MP on Twitter using the pseudonym Tim Cavendish.

He claimed he had information about Piers Morgan and the telephone hacking scandal engulfing the News of the World.

Mrs Mensch sent him her personal gmail email address. It was to that account that Zimmerman sent the threatening message, the court heard.

The email, which was timed at 10.47pm on 22 August, was sent from an account with the address of lulz.sec@hotmail.com - a reference to the internet hacking group Lulz Security.

The email said:

"Subject: You have been HACKED :D

Louise Mensch, nee Bagshawe, the slut of Twitter.

We are Anonymous and we don't like rude c**** like you and your nouveau riche husband Peter Mensch. You have been hacked!

We are inside your computer and all your phones, everywhere... and inside your homes.

So get off Twitter.

We see you are still on Twitter. We have sent a camera crew to photograph you and your kids and will post it all over the net, including Twitter. C***face.

You now have a Sophie's Choice. Which kid is to go? One will, count on it c***.

Have a nice day

From all of us at MIT 617-253-1000"

Mr Hart said the reference to MIT followed by a US telephone number was to give the impression the email had been sent from hackers linked to the Massachusetts Institute of Technology.

Mrs Mensch was in New York with her husband recovering from an operation while her three children were with their father, her ex-husband, in the UK.

The MP took the threats seriously and immediately contacted the police, the court was told.

In a victim impact statement read to the court, Mrs Mensch spoke of her terror at receiving the threat.

"I was terrified on behalf of my children. I was in New York with my husband recovering from an operation and my children were with their father and to receive a threat like this made me very upset," she said.

"I was 3,000 miles away from my children and I was worried for their safety and the safety of my ex-husband. I felt powerless to do anything."

Mrs Mensch said that after receiving the email she was sent a Twitter message from someone called "Robert Redford".

"He made reference to the contents of the email and that one of my children would die and it made me believe he was responsible," she said.

Zimmerman first became a suspect for threatening Mrs Mensch when Independent newspaper columnist Terence Blacker, who was a former neighbour of the defendant in London, received a similar email.

A forensic examination linked the sender of the email to the IP and router addresses of Zimmerman's Virgin Media account at his home in Gloucester.

Police visited his house and he volunteered the password for his computer, the court was told.

Examination of that computer found Zimmerman had a series of tabs on his internet browser open at the Twitter accounts of Tim Cavendish, Mrs Mensch, Piers Morgan and Lord Prescott.

He also had pages open on BBC News Online of reports of Mrs Mensch receiving threats to her children by email, an article on the News of the World hacking scandal and a story on the hacking group Anonymous.

There was also a page open for a Skype account in the name of Tim Cavendish.

Detective Constable Iqbal Azad told the court: "We were able to trace the internet service provider and it was an internet broadband account held by Mr Frank Zimmerman at his home address."

Judge Brown said he had to rule on whether the email sent to Mrs Mensch was malicious, and if it was, had Zimmerman sent it.

He said he was satisfied the email was malicious and added: "The court needs to be satisfied that this email can be linked to the defendant.

"The very helpful evidence of Det Con Azad has been clear that there is a direct link to the IP address that has been identified as coming from Mr Zimmerman's computer.

"It does not appear in question in my mind that the prosecution have established a direct link by the email received by Louise Mensch and the computer that was found at the defendant's address.

"I can be satisfied that this was a malicious communication sent by Mr Zimmerman from his computer at his home address.

"I can therefore be satisfied that he committed the act in question and the offence has been committed."

The judge said he had decided not to issue an immediate warrant for Zimmerman's arrest without bail and was releasing him on unconditional bail until he is sentenced on 8 May.

He told Mr Hart: "If he does not attend on that date, and unless circumstances change, he must understand I am being left with very little alternative but to issue a warrant."

Following the judge's ruling, Mr Hart said the Crown would be applying at the sentencing hearing for a restraining order against Zimmerman, preventing him contacting "other high-profile individuals".

Details of the proposed order were not revealed in court.

Speaking afterwards, Mr Hart, who is part of the Crown Prosecution Service's special crime and counter-terrorism division, said: "The right to freedom of speech is accompanied by laws that protect individuals from those who seek to abuse that freedom and use the anonymity of email or Twitter accounts to hide from the fear that they cause.

"Zimmerman attempted to use pseudonyms and other methods to wage a campaign of fear against a high-profile person, thinking that he was safe from detection.

"He was wrong. This should be a salutary lesson for anyone who considers that they are above the law because they threaten others through a computer rather than on the streets.

"I would also like to thank officers from the Metropolitan Police Central e-crime unit for their hard work."