Judas’ surname is more probably a corruption of the Latin sicarius (“murderer” or “assassin”).
He was their treasurer. John 12:6 introduces Judas’ thievery by saying, “. . . as he had the money box he used to take what was put into it.

John 12:6 designate Judas’ motive as avarice, but Luke 22:3–6 ascribes his action to the entrance of Satan into his body, paralleling John 13:27, where, after Judas took the bread at the Last Supper, “Satan entered into him.” Jesus then says, “What you are going to do, do quickly.” This is the culmination of John 6:70–71, which, after Jesus says, “Did I not choose you, the Twelve, and one of you is a devil?” discloses that he meant “Judas the son of Simon Iscariot, for he, one of the Twelve, was to betray him.”