Eyewitness News reporter NJ Burkett has the latest.
The letters are being described as a bizarre coincidence, but a ranking law enforcement official briefed on the investigation tells Eyewitness News that a new image has been recovered of the bomber from a camera at 38th Street and 5th Avenue. This is one block from where the bike was apparently discarded. That neighborhood is being scoured by detectives for clues.
The image is said to be grainy, but it is being enhanced. Other images are also being examined in an attempt to track the suspect's movements away from the bombing scene.
Although the dumpster where the bike was ditched is not covered by any surveillance cameras, someone was seen walking away from the area who may fit the general description of the suspect.
Friday morning, NYPD Commissioner Ray Kelly said authorities are analyzing video from literally dozens of cameras.
"It's important that we know the route he took," Kelly said. "He goes south, obviously, there's a lot of cameras in the Times Square area. We're in the process now of identifying those cameras.
The explosion happened at 3:40 Thursday morning. It was strikingly similar in almost every way to two previous early-morning bombings at the Mexican and British consulates.
The NYPD is denying reports that the bomber claimed responsibility in a series of letter addressed to members of Congress. The letters included a photo of the recruiting center, but included no explicit theat.
Authorities are looking into an incident on the Canadian border, in which passengers fled their car when questioned. Agents recovered photos, which included the recruitment center. But sources tell Eyewitness News that none of those individuals are believed to have entered the United States.
None is believed to be the bomber, who is described as a man large in stature, but carefully covered up.
"We had a witness today who said he saw an individual wearing a hooded jacket," Kelly said. "What was unusual to him, although it was cold, it wasn't cold enough to require an individual to have to have virtually everything covered."
A reward is being offered, and anyone with information is urged to call police.
Sources also tell Eyewitness News that enhancement of the main surveillance video of the scene now indicates that the bomb was detonated by a fuse, and not a timing device or remote detonator.
The video shows the suspect cycling up to the recruiting station and planting the device at the door. Then he rode away and a minute later, the crude bomb exploded. When the smoke cleared, there were no injuries or serious damage to the structure.
Kelly said the device, though unsophisticated, could have caused injury and even death.
Police have two other bombings for comparison. There was an attack last year on the Mexican Consulate and a 2005 bombing at the British Consulate.
In all three cases:
The earlier attacks, however, involved two devices each, modeled after grenades.
The Times Square attack involved just one boxed device.
