WASHINGTON - With Baltimore Mayor Martin O'Malley at his side, police Commissioner Edward T. Norris appeared at a national law enforcement conference yesterday and said he couldn't do his job without the mayor's backing.

"If you don't have the support of your chief executive, you can't do this job," Norris said in a downtown hotel ballroom packed with police officers and other officials from around the country. They were gathered for a three-day conference on community policing.

Norris recalled the criticism he faced after Sept. 11, when he deployed city police to protect Baltimore against a possible terrorist attack. He said the mayor backed him during that time, even in the face of complaints from state Sen. Nathaniel J. McFadden, who said the city needed to focus on conventional crime because "Osama bin Laden is not on Caroline Street."

"Two weeks ago, we arrested one of the hijackers' roommates - two blocks from Caroline Street," Norris said to loud applause. The man, Rasmi Al-Shannaq, faces visa fraud charges along with a charge of remaining in the United States after his visa expired, but authorities have not linked him to the Sept. 11 terrorist plot.