Toronto Mayor Rob Ford's whereabouts remain a mystery after he quietly returned from the U.S. last week, raising questions about whether he made it to a rehab facility.

Last Thursday, Ford left his home and boarded a plane to Chicago after he announced he was a taking a leave of absence to seek help for substance abuse. Ford, however, decided to turn back to Canada.

Roy Norton, the Consul General of Canada in Chicago told CTV News on Tuesday that Ford arrived in Chicago last week but after speaking to U.S. Customs and Border Protection, "he withdrew his request to enter the U.S.A. and departed."

It is not known why Ford withdrew his application after flying to Chicago, nor is it known where the mayor went after his plane turned around.

Jamie Ruiz, a spokesperson for U.S. Customs and Border Patrol, told CTV News that the agency cannot confirm any specific information in accordance with U.S. law, but outlined the general criteria of why someone may be denied entry.

According to immigration lawyers, admitted drug use in either the U.S. or a foreign country is often a reason a traveller may be denied entry.

"If (Ford) admits the essential elements of the offence of possession, which he's done publicly, he can actually be barred for that reason," lawyer Henry Chang told CTV News on Tuesday.

News of a video that appeared to show the mayor smoking crack cocaine broke nearly a year ago. Since then, the embattled mayor has faced a series of scandals, including damaging reports last week containing new allegations about drug and alcohol use and inappropriate comments about a colleague. His brother, Coun. Doug Ford, however, has steadfastly stood by his side.

On Tuesday, the Ward 2 councillor told reporters at city hall that although the mayor is not in Chicago, he is in rehab and "feeling great."

"He's in a rehab facility, 100 per cent, and he's getting the support that he needs," Doug Ford said Tuesday morning. "He's bought into the program and he's getting the support that he needs."

Ford's lawyer, Dennis Morris, also said that the mayor had checked into rehab, but declined to disclose his client's location.

It was rumoured that Ford was staying at a rehab facility in Guelph, Ont., but the addictions centre told CTV Toronto they would neither confirm nor deny anyone's presence.

Some councillors, however, are questioning whether the mayor is receiving treatment for substance abuse.

"I would ask that some form of document be shown by an expert, a doctor in that field that may be treating him," Coun. Giorgio Mammoliti told CTV News on Tuesday.

The mayor has not released any statements since last week. According to Wendy Cope, the director of the Bellwood Health Services, substance abuse patients are generally limited from contacting the outside world so soon after being admitted.

"They need to give in their cell phones, for instance, as soon as they come in," Cope told CTV News. "So they're not allowed to make phone calls unless they've been approved."

But Ford apparently spoke to Coun. Denzil Minnan-Wong on Tuesday, after speaking to his brother Doug.

"It was a friendly conversation," said Minnan-Wong, who also declined to disclose the location of the facility where Ford is staying.

"If the family or Rob wants that to be known, it will be free for them to disclose it," he said. "It is not my place."

Minnan-Wong said the mayor was in "good spirits" and that Ford had asked about what was going on at city hall.

"I do think Rob misses council and what's going on here," he said.

DECO Labels and Tags, the business owned by the Ford family, has its U.S. headquarters in Chicago, and the Fords maintain a residence in the city.

Those ties to the Illinois city fuelled speculation that Ford flew there to check into a local rehab facility, but there was no confirmation that Chicago was the mayor's final destination.

With a report from CTV News' Katie Simpson