"However, he wasn't linked to this particular assault until just this past week," Armstrong said.
"He was in Canada illegally under the assumed name of Robert James Clarke. Police say he had been here for two years and was working as a handyman in the Vancouver area, but authorities are not sure why he chose to flee to Vancouver in the first place."
Armstrong said Farley was assumed to have used an altered passport to enter Canada.
"But just exactly how he made it past all those levels of security at the airport, and immigration wise, we're not sure at this point.
"We understand that border officials in Canada are doing an investigation and they're certainly in touch with police in New Zealand, as well as Interpol, to find out exactly how he got into Canada."
Farley plans to apply for bail when he appears in court on Thursday, but Armstrong said it was "highly unlikely" it wanted to be granted.
He is charged with eight offences, including aggravated sexual assault, assault causing bodily harm and kidnapping.
Armstrong said authorities wanted to deal with the sex charges first, before dealing with the immigration matter.
It was possible Farley would then be extradited back to New Zealand. Theoretically, he could be sent back to New Zealand to serve his sentence here, if convicted.
Officers allege the 42-year-old victim was picked up against her will, driven to a secluded area, tied up and beaten during the incident, the Huffington Post reported.
Several witnesses called 911 as they watched the woman being dragged behind a white van down a city street.
Police believe the woman partially freed herself and, fearing for her life, attempted to jump from the moving vehicle.
The woman, who has since been released from hospital, suffered serious injuries, including to her head, but was able to give a description of her attacker.
The New Zealand police website said Farley was wanted for breaching home detention and attempting to pervert the course of justice.
It said he was "believed to be in the Hawkes Bay" area.
