It is one of the twelve apostles (Mk 14:20-14:20)

“Jesus said to them.

‘It is one of the twelve!

It is the one

Who is dipping

Into the bowl

With me.’”

 

ὁ δὲ εἶπεν αὐτοῖς Εἷς τῶν δώδεκα, ὁ ἐμβαπτόμενος μετ’ ἐμοῦ εἰς τὸ τρύβλιον.

 

This is similar to Matthew, chapter 26:22, and Luke, chapter 22:21, where Jesus’ hand was on the table.  John, chapter 13:26-27, has the dipping of the hand in the bowl for bread in a conversation between Jesus, Peter, and Judas.  Here, Mark said that Jesus told his apostles (ὁ δὲ εἶπεν αὐτοῖς) that clearly the betrayer was one of the 12 apostles (Εἷς τῶν δώδεκα).  In fact, he said that it was one of those who were dipping into the bowl or the deep platter with him (ὁ ἐμβαπτόμενος μετ’ ἐμοῦ εἰς τὸ τρύβλιον).  There was no question that the betrayer was among them in this room.