In the current off-the-rails subway assault, a good Samaritan was bitten and choked on the D train at Columbus Circle on Saturday.

Around 5 p.m., the perpetrator was threatening a passenger on the uptown train when another straphanger interfered, according to police.

According to the NYPD, the attacker turned his rage on the 20-year-old volunteer and assaulted him with his mouth and hands.

According to police, the suspected attacker, 44-year-old Billy Torres, was arrested while the victim was taken to the hospital for treatment of his injuries. As of late Saturday, no charges had been filed.