VANCOUVER (CP) A woman was sentenced to 18 years in prison Thursday after pleading guilty in the horrific death of a former Whitehorse resident at a notorious crack house known as the House of Horrors''.

Joanna Larson, a 37-year-old mother of three, was originally charged with the first-degree murder of prostitute Annette Allan.

However, she pleaded guilty to manslaughter before the scheduled start of her trial in B.C. Supreme Court.

Allan lived in Whitehorse from 1993 to 1998 with her then-boyfriend, Len McGinnis.

Crown counsel Christopher McPherson and defence lawyer Simon Buck told Justice James Williams at a hearing Wednesday that a sentence of 18 years in prison would be appropriate for the April 2001 beating death of Allan. The deceased frequented the rundown bungalow in suburban Surrey visited by addicts looking for drugs.

Allan's body was found floating in the Fraser River on June 4, 2001. Her bruised body was bound and gagged and she had been stabbed nine times.

The official cause of death was asphyxiation. An autopsy found high levels of methamphetamine in Allan's body.

McPherson told court that Larson, a street prostitute and alcoholic known as Jo Jo, had accused Allan, 27, of being a rat'' the morning of the beating that took place in the bathroom of the so-called House of Horrors, which has since been demolished.

Sex trade workers and drug addicts frequented the derelict stucco North Surrey rental home.

The RCMP have said a number of assaults, extortion, even torture happened in that house.

Calling it a horrific, horrifying case,'' McPherson said Allan was stabbed and beaten with a hammer before being wrapped in plastic, thrown into the trunk of a car and driven around the Lower Mainland for eight hours before being dumped in the river.

He said Allan was alive when she was put in the trunk but died sometime later while still confined there.

McPherson told Williams that Allan was treated like a disposable human.''

In Whitehorse, the woman had worked at various bars, hotels and restaurants, including the 60 Below, a bar in the Pioneer Inn's basement that no longer exists; the Great Wall Restaurant; the Roadhouse off-sales store and the Fort Yukon Hotel, now the Roadhouse Inn.

One former acquaintance remembers Allan as a nice person with problems, while another recalls that Allan left Whitehorse with her share of enemies. She'd been using drugs, likely cocaine, while she was in the Yukon.

Debbie Johnson worked with Allan at the Roadhouse off-sales for about eight months in 1998, and said Allan headed to Victoria before she ended up in Surrey.

Larson's co-accused, Francis Joseph Gauthier, 36, who drove the car, was sentenced to 18 years in prison last year for his part in Allan's death. Gauthier was also initially charged with first-degree murder but pleaded guilty to manslaughter.

Another man charged in the death, Joseph Legassie, was found not guilty in 2003 of the unlawful confinement of Allan.

Buck told court that Larson is attempting to take full responsibility for the killing and said she has no good reason for what she did.

He said Larson had a normal, productive life as a young woman but things spiralled out of control at 19 following the drowning death of her two-year-old child.

Larson turned to alcohol, attempted suicide and suffered from mental-health problems. He said she was an alcoholic who drank to excess everyday.

She has been in custody since Jan. 11, 2002. Since then, she was convicted and sentenced to four months for a Jan. 8, 2002 robbery.