TORONTO - The mystery of Toronto Mayor Rob Ford's whereabouts deepened Tuesday, after reports that he did not enter the United States as expected but instead returned to Canada after landing at a Chicago airport.

Ford's attorney said last week that the mayor had left Toronto for rehab after a video surfaced that appeared to show him smoking a crack pipe late last month - nearly a year after reports of an initial video that appeared show him smoking the drug. The lawyer, Dennis Morris, said Ford's plane was headed for Chicago.

But Roy Norton, the consul general of Canada in Chicago, told the Globe and Mail that Ford voluntarily withdrew his application to enter the United States when he landed and was "not denied entry, per se." Norton didn't return messages left by the Associated Press, and Canada's foreign affairs department deferred comment to U.S. officials.

Kris Grogan, a spokesman for U.S. Customs and Border Protection, said in an e-mail that the federal Privacy Act prevents officials from commenting on "an individual's processing," but he noted that anyone hoping to enter the U.S. must "overcome ALL grounds of inadmissibility." He said there are more than 60 grounds for inadmissibility, including criminality, security reasons and documentation requirements.

Once a foreign visitor is formally denied entry, he or she has to receive special permission from the government to try to come back. If Ford decided on his own not to ask immigration authorities to let him in, future visits could be as simple as presenting his passport at the border.

The last time Ford visited the United States was in early March, when he appeared on the Jimmy Kimmel Live television show in Los Angeles.

Morris and Doug Ford, Rob's brother, declined to discuss the Globe's report, but insisted Tuesday that the mayor is in rehab.