Washington ? Now that Osama bin Laden has again placed himself in the public eye – or, at least, in the public ear – with a threatening audiotaped statement, U.S. counterterrorism officials wonder if he has taken on a new look.

Because he delivered his message via audio, rather than video, intelligence officials suggest bin Laden may have wanted to conceal his appearance. Officials have only a suspicion, but no evidence, that his appearance may have changed since his last videotaped statements from roughly a year ago.

The al-Qaida leader’s whereabouts remain unknown. According to U.S. officials, America’s best bet for his location has not changed: the wild mountains along the border of Afghanistan and Pakistan, a remote tribal region where U.S. and allied forces fear to go.

The one-time Saudi aristocrat looked haggard and gaunt in one of his last videos, which was probably filmed in Afghanistan in late November or early December 2001. Counterterrorism officials believe he was sensitive to the widespread reporting that described him as such, and may be trying to hide ailments and injuries from public view.

One thing he cannot change is his height: He stands at least 6-feet-4.

Bin Laden is not above using misdirection to foil pursuit. Before the war in Afghanistan, he used look-alike decoys and fake caravans, and he is believed to have moved around the country hidden in an ambulance.