Barabbas

Was Barabbas' only crime robbery?
Barabbas was also a murderer and a rebel: "And there was one named Barabbas, who was chained with his fellow rebels; they had committed murder in the rebellion" (Mark 15:7). And we learn more about Barabbas in Matthew 27:15-23: 15 Now at the feast the governor was accustomed to releasing to the multitude one prisoner whom they wished. 16 And at that time they had a notorious prisoner called Barabbas. 17 Therefore, when they had gathered together, Pilate said to them, “Whom do you want me to release to you? Barabbas, or Jesus who is called Christ?” 18 For he knew that they had handed Him over because of envy. 19 While he was sitting on the judgment seat, his wife sent to him, saying, “Have nothing to do with that just Man, for I have suffered many things today in a dream because of Him.” 20 But the chief priests and elders persuaded the multitudes that they should ask for Barabbas and destroy Jesus. 21 The governor answered and said to them, “Which of the two do you want me to release to you?” They said, “Barabbas!” 22 Pilate said to them, “What then shall I do with Jesus who is called Christ?” They all said to him, “Let Him be crucified!” 23 Then the governor said, “Why, what evil has He done?” But they cried out all the more, saying, “Let Him be crucified!”

Did Pilate know the Jews’ real motive for wishing to have Jesus killed?
"He knew that they had handed Him over because of envy" (Matthew 27:18).

How might his wife's message have influenced that impression?
Most probably confirmed it.

Why did Pilate offer Barabbas as an alternative to Jesus?
Since the crowd was calling for the death of a rebel leader, Pilate was offering them a real one, betting that they would be forced to choose Jesus over a murderous rebel. This was Pilate's second attempt to avoid crucifying Jesus.

Did it work?
"And they all cried out at once, saying, “Away with this Man, and release to us Barabbas” - who had been thrown into prison for a certain rebellion made in the city, and for murder" (Luke 23:18-19).