An Abbotsford, B.C., man who slit his five-year-old stepdaughter's throat with a kitchen knife while vacationing in the U.S. has been given a sentence twice as long as the standard jail time for the crime.

Peter James Wilson, 29, was sentenced Friday in a Washington State courtroom for the aggravated first-degree murder charge for killing young Clare Shelswell. The justice gave Wilson, who admitted to the crime and waved his right to a speedy trial, 664 months of jail time -- just over 55 years.

Wilson admitted to American detectives that he killed the girl on June 27 following a dispute with her mother, his wife Sarah Wilson, while the family was staying at a rental vacation home near Lake Cushman, Washington.

At Friday's sentencing, Wilson apologized in tears, saying he now wished he could give his life for hers.

The girl's mother spoke as well, honouring her young daughter's memory.

Prosecutor Gary Burleson asked for an exceptional sentence in the case beyond the standard range of 20-26 years because of the aggravating circumstances in the murder.

A local police chief called the crime the most horrific he'd seen in 37 years on the job.

"The violence toward a five-year-old girl is just horrific and senseless," Mason County Deputy Chief Dean Byrd said.

The case

According to court documents, Wilson and his wife were arguing about disciplining the girl when he said that he would "take care of it."

Wilson then took the girl downstairs to the home's kitchen and slit her throat. Wilson's wife told investigators that after hearing screaming she ran downstairs and saw her daughter in a pool of blood clutching her throat.

Despite attempts to save her life, the child died in her mother's arms.

From the start of the trial, prosecutors asked for an exceptional sentence in the case because of the aggravating circumstances in the murder.

The charge of first-degree murder with aggravating circumstances meant the judge could impose a sentence beyond the standard range of 20-26 years. Wilson also pleaded guilty to committing murder with a deadly weapon, which added another two years to the sentence.

Wilson told investigators that he suffers from bipolar disorder and is taking medication.

Remembering Claire

The murder of the young girl shook the suburban city of Abbotsford.

In an interview after her death, Shelswell's pastor remembered the bespectacled youngster for her big smiles, hugs and love of art.

"She could articulate things in her soul, her heart, that few adults can," associate pastor Cam Stuart said.

"There were people who had been part of the faith community all their life, and they said, 'She prayed better than I did."'

A trust fund has been established in Shelswell's memory to support her mother and nine-year-old sister Suzy.