Marcellus Jacob, seen in this police photograph, walked out of a Vancouver halfway house on Sunday. (Vancouver Police Department)

A Whitehorse man convicted of sexual assault is once again the subject of a nationwide search, having walked away a second time from a Vancouver halfway house.

Marcellus Jacob, 27, who was convicted in the vicious 2001 rape of a Whitehorse woman, left the halfway house about 5:30 p.m. PT Sunday, according to a Vancouver police department news release.

A Canada-wide search warrant has been issued for his arrest. Jacob is considered to be at a high risk to re-offend.

Police describe him as aboriginal with dark spiky hair, about five feet four inches in height, and weighing 170 lbs. He was last seen wearing a red sweater, black pants and black runners, police said.

Jacob was serving a seven-year sentence at a B.C. prison for sexual assault and break-and-enter, but Vancouver police say he also has a long history of violence and property-related offences.

In sentencing Jacob in 2002, Yukon territorial court Judge Barry Stuart described Jacob as a "ticking time bomb," adding that he had a "propensity for violence and for sexually inappropriate behaviour."

The National Parole Board first released Jacob into the Vancouver halfway house in October 2006, after he had served two-thirds of his sentence.

But Jacob disappeared a month later, sparking a nationwide search. He turned himself in four days afterward.

In May, the parole board decided to give Jacob a second chance, releasing him on day parole with a strict curfew and other restrictions attached.

Jacob was brought back to prison in late June, about six weeks after his release, but was quietly returned to the halfway house after an undisclosed period.