An MP said today he was horrified at the early release of a killer who stabbed a woman to death and threatened the victim's family.

American Curtis Howard, who pleaded guilty to manslaughter on the grounds of diminished responsibility, served only seven years of a life sentence for the death of Catherine Ayling.

He has now been deported, after convincing the parole board at HM Prison Whitemoor in Cambridgeshire he no longer posed a threat, but Catherine's sister Sylvia Hartigan, 39, fears Howard may get back into the country and hunt her down.

Howard Flight, MP for Arundel and South Downs, said: "This is a dreadful case and looks to me to be very irresponsible.

"I was horrified to learn of the Parole Board's decision and have demanded the Minister of State at the Home Office, Keith Bradley, explain on what basis Howard was released and what protection can be afforded to the victim's family who are understandably frightened that Howard may once again evade UK immigration control and return to carry out his threat."

During the trial in 1994, the judge said that Howard posed a threat to the family. Mr Justice Hidden told Howard: "Even after the death of Catherine, it is necessary to protect the public and particularly her sister and her husband from serious harm from you."

Catherine was subjected to a frenzied knife attack and her body was found dumped in the boot of a car at Gatwick Airport in 1991.

Before killing her, Howard broke into Mrs Hartigan's former home in Wick, Littlehampton, and etched "Catherine is dead" on the furniture.

The 6ft 4in computer science student, who had a long history of mental illness, became infatuated with 24-year-old Catherine, a former Worthing College student from Arundel, after she went on a six-month student exchange trip to the US in 1989.

He continued to pester Catherine by phone after she returned to Britain and crossed the Atlantic to see her.

Howard was deported after wrecking Mrs Hartigan's home, but slipped back into Britain in 1991 using a false passport.

He tracked Catherine to a college in Cheshire and killed her before fleeing to the States, from where he was extradited to stand trial.

Mr Flight said he first took up the case two years ago when Howard was considered for release, but "to the relief of everyone" he was kept behind bars.