Law & Order: Criminal Intent (2001)

Season 2: Episode 20

The detectives investigate a murder of a math student who worked in a poker club as a card-counter. Their case brings the detectives to a group of computer nerds, but later they discover a computer gambling system which has tougher suspects. The detectives discovers that even there own workstations are hit by the ringleader of the group, who had bigger plans for his horseracing and other scams.