The writer of the gospel of John worked really, really hard to make it clear that no one suspected Judas:
This is John 13:21-20, with commentary:
21 When Jesus had thus said, he was troubled in spirit, and testified, and said, Verily, verily, I say unto you, [this is the stock phrase that Jesus uses when he means 'what I am about to tell you is really, really important'] that one of you shall betray me. [ He had to tell them. They didn't know at this point--and at this point, Jesus' public ministry is finished.]
22 Then the disciples looked one on another, doubting of whom he spake. [They don't say, "Ah-ha! I just knew something was up with Judas!" They look around at each other, searching for a guilty face, because they have no clue who will betray Jesus.]
23 Now there was leaning on Jesusâ€™ bosom one of his disciples, whom Jesus loved.
24 Simon Peter therefore beckoned to him, that he should ask who it should be of whom he spake. [Simon Peter has no clue who the betrayer is.]
25 He then lying on Jesusâ€™ breast saith unto him, Lord, who is it? [The 'beloved disciple' has no clue who the betrayer is.]
26 Jesus answered, He it is, to whom I shall give a sop, when I have dipped it. And when he had dipped the sop, he gave it to Judas Iscariot, the son of Simon. [Jesus devises a sign. So they should know who it is now, right?]
27 And after the sop Satan entered into him. Then said Jesus unto him, That thou doest, do quickly.
28 Now no man at the table knew for what intent he spake this unto him. [Even after hearing this suspicious sentence--even with the sentence falling hard on the heels of 'one of you shall betray me'--they don't get it.]
29 For some of them thought, because Judas had the bag [They trusted Judas so much that they let him be the CFO; they are so UNsuspecting of him that they think this statement is more likely to have to do with his financial role than it is to have to do with the topic at hand--who will betray Jesus.], that Jesus had said unto him, Buy those things that we have need of against the feast; or, that he should give something to the poor. [They come up with these completely innocent explanations for Jesus' words--it doesn't even occur to them as a possibility that Judas might be a betrayer.]
30 He then having received the sop went immediately out: and it was night.
If the author had stood on his head or jumped up and down, it could hardly have been made clearer that, even at this late point in Jesus’ ministry, the disciples have no clue that Judas will betray Jesus.
What are the implications of this? Why is it important to know that the disciples didn’t suspect Judas? What could this teach us about us? And why do artists always make Judas look like a bad guy?