Every cop in America is looking for a US citizen, one of three alleged Al Qaeda terrorists believed to be on the loose in the U.S.
He's Jude Kenan Mohammad. He's was born in Florida. He's 22 years old and only 5' 6" and 160 pounds.
The FBI say he's armed and dangerous.
"He knows New York, he was born and raised on the east coast. This a guy who can stay one step ahead of law enforcement, who knows the vulnerabilities, who knows how we operate," said FBI official Robert Strang.
The high school drop-out was indicted, along with co-defendants, for his alleged part in a terror plot in North Carolina in 2009.
He fled to Pakistan but is now believed to be back in the U.S.
"[Terrorists are] told to do as much damage as possible. Go through the road blocks, run people over, try to get to your target, and to where you can cause the most harm," said Strang.
Police in New York and elsewhere continued to search for him and two other suspects, setting up checkpoints and stopping any vehicle that could contain a bomb. They even had a tank ready, and carried radiation detectors.
The security scare is discouraging travel. In the U.S. a Delta Air lines flight to New York from London was almost empty on 9/11.
An image of President Obama speaking from behind a bulletproof screen at the 9/11 memorial Sunday is shocking many Americans, but underlined the seriousness of the threat.
The First Lady, President Bush, and his wife Laura, were also shielded by massive bulletproof screens.
The 9/11 memorial was open to the public Monday for the first time and thousands were expected to visit.
Only relatives of those who died on 9/11 were allowed access to the site Sunday, and there were indelible images of raw emotion as the grieving relatives found their loved ones names on the memorial for the first time.
Now the rest of America is joining them in solemn remembrance.
To find out how you can reserve tickets to visit the memorial go to, http://visit.911memorial.org