Developed by three Canadian programmers in Silicon Valley in California, it allows senders to create multiple links to a large file so it can be viewed by an unlimited number of people. Users type in their e-mail addresses, upload the file and YouSendIt creates a free, anonymous Web page for them. To distribute videos of the contractors who were kidnapped this month, Abu Maysara created dozens of links using YouSendIt and sent them to chat rooms all over the Internet.
He compressed the files, or made them as small as possible, investigators said, so that they could be copied more quickly. By the time U.S. officials got word of the videos, they had been anonymously copied from computer to computer as fast as a Top 10 music hit would have been during the peak of the music service Napster's operations -- making it impossible to locate, much less destroy, all the copies of the video.
Khalid Shaikh, president of YouSendIt Inc., based in Campbell, Calif., said he created the program to help families trade pictures and videos and to help colleagues at work share files such as multimedia presentations. He said he was surprised and saddened to hear that the technology was being used to spread violent messages.
Shaikh said he had not been contacted by any law enforcement authority regarding the use of his service by terrorists but that he would be eager to help U.S. officials. But, he said, since there are more than 1 million file transfers a day on YouSendIt, it would be impossible for the company to monitor them all.
"It's almost like policing a society," he said. He also said the company's philosophy is to let users monitor each other. The company recently added technology to allow viewers to have a link deleted if they deem it offensive.
The messages from Abu Maysara follow a rigid format. They are always in Arabic and open with a standard greeting such as, "In the name of Allah, Most Gracious, Most Merciful." Then comes the heart of the message, written in flowery language, recounting an attack. Abu Maysara favors ellipses, writes in half-sentences and mixes the details of an incident with religious invocations.
In some chat rooms, Abu Maysara and his collaborators are hailed as heroes. On Sept. 22, after he announced the beheading of Eugene "Jack" Armstrong, 52, a native of Hillsdale, Mich., dozens of people on one Web site thanked him and Zarqawi.
"I love you, I love you, O slaughtering Sheikh!" one person wrote, according to a translation by the SITE Institute. Another said that he would "pray to Allah that He protect you, O Mujahideen of Iraq."
On occasion, chat room participants act like fans and pummel Abu Maysara with questions about his background and how and why he joined the group, said Kohlmann, the terrorism expert.
All they get from Abu Maysara is silence. "He doesn't respond to requests for information. He's never replied to any message. He's almost like a robot," Kohlmann said. "He never gets involved in the discussion. He never explains himself."
Still, many of the people who read Abu Maysara's postings follow up with advice about new attack strategies. In the past, Katz said, Abu Maysara seemed to ignore them, but in recent days Katz noticed something that was either a remarkable coincidence or a change in Abu Maysara's habits.
In a posting on Sept. 22 at 3:46 a.m., time zone unspecified, a person calling himself Nimr suggested that the group make Kenneth Bigley, the 62-year-old British citizen who had been kidnapped with Armstrong and another American, Jack Hensley, 48, of Marietta, Ga., beg for his life to the "tyrant."
A few days later, a clip appeared on the Web site with a distraught Bigley pleading to British Prime Minister Tony Blair to save him.
Staff writer Nora Boustany and researchers Robert E. Thomason in Washington and Richard Drezen in New York contributed to this report.