LONDON, England (CNN) -- A former royal aide convicted of murdering her boyfriend has failed to return to prison on schedule, British police said Tuesday.

Jane Andrews, 42, did not report back to East Sutton Park prison, southeast of London, on Sunday night, Kent Police said.

"We have no information to suggest she is a threat to the general public, however we must be mindful that... she was convicted of murder," Assistant Chief Constable Andy Adams said in a statement calling on the public for help in finding her.

Andrews worked as a personal dresser to Sarah Ferguson, then the Duchess of York, for nine years until 1997.

She was convicted of murdering Thomas Cressman, 40, in their London home in a fit of rage in 2000.

During the month-long trial in 2001, the Old Bailey criminal court in London heard that Andrews was an "intense person" who stabbed her lover to death while he slept after he refused to marry her.

The court heard she beat Cressman over the head with a cricket bat while he was still in bed and then stabbed him with a large kitchen knife.

Andrews was transferred from a closed prison to an open one -- which allows prisoners to come and go on a fixed schedule -- in July. On November 18 she was sent on East Sutton Park, which is also an open facility.

"We are becoming increasingly concerned for Jane's welfare and would urge anyone who has any information that will help us locate her safe and well to come forward," Adams said Tuesday.

Andrews apparently attempted to commit suicide after killing Cressman, the court heard during her trial.

She was found in the west of England three days after the killing, in her car by the side of the road, having taken an overdose of painkillers. She was hospitalized for three days.

The Prison Service describes the prison that housed her as "a pleasant mansion house overlooking the Weald of Kent. It holds both adult and young offender women in open conditions preparing them for resettlement in the community."

Andrews was transferred there only four days before she disappeared.