The court's decision to refuse to hear her case has dealt a crushing blow to the 42-year-old former lawyer's hopes of ever getting out of prison. Carpenter was spared the death penalty under the terms of her extradition from Ireland.

She is serving a life sentence after being convicted by a jury in New London, Connecticut in 2002, in what local media describe as a "sordid case involving sex, drugs, murder for hire and a vicious custody battle over Carpenter's three-year-old niece."

The decision of the US Supreme Court was welcomed by the family of Anson 'Buzz' Clinton, who was shot dead by a hitman in the Connecticut town of East Lyme in March 1994.

Clinton was married at the time to Carpenter's sister, Kim.

"Beth's bad news is my good news, " said Clinton's mother Dee. "It's just one more nail in her coffin."

Local media said the potential for any further appeals would be limited.

One of Carpenter's lawyers was quoted as saying that since she had no chance of release under the capital felony conviction, she would likely file a 'habeas corpus petition'.

"The chances of success lessen, but there is still hope, " the attorney said, adding that her client was "doing as well as can be expected for someone who is serving a life sentence."

Carpenter's conviction had previously been upheld by the Connecticut Supreme Court. That court rejected her claims that the trial judge had made mistakes by improperly including and excluding evidence. She has been held for the last four years in the York Correctional Institution.

Carpenter fled to Ireland around the time that investigators began to focus on her involvement in the case.

She was arrested in Sandymount, Dublin, in November 1997, after living here for most of that year. Although she initially challenged her detention in Ireland, she later withdrew the challenge, clearing the way for her extradition.

Along with capital felony and murder convictions, Carpenter was also convicted of conspiring with fellow attorney Haiman Clein, whom the US media describe as "her cocaine-snorting boss and former lover who hired the hitman to kill Clinton".

According to affidavits read in court in Ireland during her extradition proceedings, the murder had its origin in Carpenter's objections to her sister's marriage to Clinton. She was "obsessed" with her niece Rebecca, the sister's daughter by a previous relationship. She disapproved of Clinton and, along with her parents, sought custody of Rebecca.

According to a statement from Clein, she began pressing him to kill Clinton and a plot was hatched with another man, Clein's cocaine supplier.