Of all the mystery surrounding the impaired driving arrest of a woman who was behind the wheel of Toronto Mayor Rob Ford's Cadillac Escalade, one of the most curious ones so far is this: What happened to the licence plates?

According to Ontario Provincial Police, 36-year-old Lee Anne McRobb was charged Tuesday with impaired driving by officers based in Bracebridge, in Ontario's Muskoka cottage country. Though the OPP declined to release information about the vehicle's owner – Ms. McRobb was given permission to drive the car by the owner, they said – the mayor's brother Doug Ford confirmed to The Globe that it was the mayor's SUV.

The licence plates, which would identify the SUV as the mayor's, have been removed from the vehicle which is required to remain in an impound lot for a week – but it's unclear how that happened.

Story continues below advertisement

According to Constable Drake, the plates were still attached when OPP officers handed the vehicle to Northland Towing and Recovery on Tuesday.

Dennis Bell, who works at the Glen Orchard General Store near where Ms. McRobb was arrested, also said he saw the plates intact when it was picked up by a tow truck.

But Northland's owner, Bob Hoolans, said that neither he or any of his employees removed any plates. "All we do is tow," he said. "We're called, we hook the vehicle up, we tow it in, put it in a compound, and lock it up."

He said that no one else – except for Ms. McRobb, who dropped by briefly on Wednesday to pick up a duffle bag and some knitting supplies from inside the SUV – has had access to the vehicle.

Councillor Doug Ford, who gave the Escalade to the mayor as a birthday gift in 2012, said "that's his car," but added that he doesn't know about the plates, either.

The councillor said he has been unable to reach his brother on the phone since the news broke Wednesday, and by Thursday evening he said he had stopped trying. "That's it," he said.

Asked if he still expected his brother to return from rehab and campaign for re-election, the Etobicoke councillor, who also is the mayor's campaign manager, said that will be up to him. "I'll wait until I talk with Rob. Rob will make that decision."

Story continues below advertisement

According to Ontario Ministry of Transportation records, the licence number normally attached to Mr. Ford's SUV is still active and registered to the vehicle.

Another mystery is how Ms. McRobb knows Mr. Ford.

Constable Drake said Ms. McRobb, who is not known to police, was arrested after a concerned citizen called about a motorist "driving erratically, drifting into oncoming lanes."

In a video posted by Muskoka's Moose FM, Ms. McRobb is seen walking around the impound lot Wednesday, telling reporters that she thinks her missing watch is "in Rob Ford's room," and that she'd met him in rehab recently.

On Thursday, Ms. McRobb's sister Lindsay Sarrasin, called Lee Anne her "best friend."

"She's a great person. She's got into some trouble, and hopefully we can fix all that," she said.

Story continues below advertisement

Ms. Sarrasin confirmed that a Facebook photo showing a young woman holding a firearm is Lee Anne, and said the photo was taken during a trip a few years ago to Las Vegas.

Ms. McRobb is a long-time Muskoka resident, whose family has a cottage business in the area, said Bill Miller, the owner of a bait and tackle shop who saw the arrest happen. Mr. Miller, a former TD Bank employee, said that Ms. McRobb – the mother to a school-aged boy – used to work as a teller at a local branch, but stopped recently due to a medical condition.

"She used to be out on a regular basis jogging here in MacTier," he said.

The embattled Toronto mayor has been on a leave of absence for the past two weeks since The Globe and Mail reported the existence of new footage showing Mr. Ford smoking what is allegedly crack cocaine. Just last week, he was spotted in cottage country, and his brother Doug told media he was out of rehab for a few hours.

The mayor's authorities have been handed to Deputy Mayor Norm Kelly, who said he has been given no indication of when or if Mr. Ford will return.

"I think many of us have gotten beyond being surprised by the stories that revolve around the mayor," he said Wednesday. "I think he should make sure that his first priority is the rehabilitation of his health."

Story continues below advertisement

With a report from Sean Tepper