For the third time in seven days, al Qaeda’s No. 2 Dr. Ayman al Zawahri has released a message on the Internet, increasing the anxiety of law enforcement officials who tell ABC News they have already been closely monitoring increased "chatter" on al Qaeda Web sites and message boards this summer. Today’s Internet posting, a four-minute audiotape message in which al Zawahri criticizes Pakistan’s President Pervez Musharraf’s handling of the siege of the Red Mosque in Islamabad, is al Zawahri’s tenth message released this year. The tape carries the logo of "as Sahab" media, an al Qaeda propaganda operation, believed by U.S. intelligence officials to be run by former Orange County California resident Adam Gadahn, who left America to join al Qaeda in Pakistan, as first reported by ABC News last year. Video Prolific al Zawahri Releases Yet Another Message U.S. intelligence officials are increasingly concerned about the use of the Internet to send hidden signals to sympathizers and cells around the world from al Qaeda’s top leadership, who are believed to be hiding somewhere along the Pakistan-Afghanistan border. In a tape released yesterday, al Zawahri added to those fears when he spoke directly of searching for information on the Internet, leading officials to worry that wherever the leadership is hiding, apparently they are somewhere with Internet access. Do you have a tip for Brian Ross and the Investigative Team?