Carl Mather was a murder victim who was the member of the notorious criminal organization known as The Fulton Street Four.
Throughout the Series[]
In the Season Two episode The Chopper all four members of the group are released from prison and Carl Mather is the first member found murdered.
Jake suspects that one member is killing off the rest in order to keep the money for himself.
A day later, another murdered body belonging to the second Fulton Street Four member lionel murray is discovered. Jake, Charles and Captain Holt team up to track down the remaining two suspects, starting with Bludsoe.