Story highlights Jason Brown, 40, faces charges of first degree gang assault and assault

Motorist Alexian Lien was beaten by bikers after bumping one with his SUV, police say

Brown is seen on video allegedly hitting Lien with his helmet, court documents say

A ninth motorcyclist has been arrested and charged in connection with the beating of an SUV driver on a Manhattan street on September 29, according to court documents.

Jason Brown, 40, was taken into custody by the New York Police Department on Monday night and was arraigned Tuesday on charges of first degree gang assault and assault, as well as third degree criminal possession of a weapon and criminal mischief in the attack of motorist Alexian Lien.

Brown is seen on video allegedly hitting Lien with his helmet, court documents state.

"Those are serious crimes ... and serious allegations against him," said Brown's lawyer Stephen Pokart. "The issue is: Do they have serious proof against him? And based on what the prosecutors offered the judge, it doesn't sound that way to me," he added.

Authorities say Lien was chased by bikers after he initially bumped one during a biker rally. When his SUV was surrounded by several bikers, Lien called 911, told police he feared for his life and drove off, running over bikers and critically injuring one.

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Lien's wife and 2-year-old daughter were in the vehicle with him. Lien has not been charged.

The chase that followed ended in traffic. Police say Lien's windows were smashed. He was dragged out of the SUV and beaten. He was treated and released from a hospital.

Brown is being held on $150,000 cash and $300,000 bond. His next court appearance is scheduled for October 25.

The NYPD, which has appealed for the public's help in identifying people in photos, hasn't ruled out more arrests or charges.

The beating drew widespread attention after a video of the incident was posted online.