Undercover cop arrested in biker attack

An undercover police officer was arrested Tuesday after allegedly lying to police about his involvement in the Sept. 29 motorcycle mob and subsequent attack of an SUV driver in New York City.

The veteran detective originally told police he didn't arrive on the scene until after the attack on Alexian Lien took place. However, video viewed by the NYPD told a different story, according to NBC New York and the Daily News.

In the video, the undercover officer can be seen smashing the rear window of the Range Rover, unnamed police sources told the affiliate. According to the reports, the new footage contradicts what the officer initially told investigators: that the attack was breaking up when he reached the scene.

"It shows him punching the back window," another unnamed source told the Daily News of the new footage reviewed by investigators on Monday. "And then as the camera is moving it catches him maybe throwing a kick at the side of the car."

After Lien was pulled from the SUV by the bikers, the undercover officer is then seen riding away. Lien was then beaten in front of his wife and daughter by the bikers, who had followed the vehicle up the West Side Highway after it clipped one of the cyclists.

NYPD Commissioner Ray Kelly said the unnamed officer, who waited several days before coming forward, had been placed on modified duty pending the outcome of an inteal investigation. Tuesday afteoon he tued himself in and was taken to Manhattan Central Booking.

The undercover officer was unarmed at the time of the attack, according to the report, and was not carrying a badge.

The rules for undercover officers when it comes to reporting crimes are often vague:

Undercover officers are required to immediately report being a witness to a crime. Uniformed officers are required to take police action if they see a crime occurring, but the rules are murkier for undercover officers who face blowing their cover, confusing civilians who don't realize the undercover is really a cop and ruining years-long investigations.

"Compromising his identity could compromise all the work he's doing and his safety as well," Michael Palladino, president of the NYPD detectives union, told NBC. "It's very difficult to lead a double life."

Four bikers have been formally charged in the SUV assault so far, and police are seeking at least two other suspects.

According to NBC, as many as five other off-duty police officers may have been riding with the hundreds of motorcyclists at the Sept. 29 annual biker event when the chase began.