When I was an accounting professor, I would warn my students that the persons likely to embezzle would be trusted employees--after all, they would be the ones most likely to have access.
This phenomenon is not new. Read Zechariah 13:1-7.
The men that Jesus chose as guards were three of his closest associates. They went to the sleep on the job. The one who sold him out to the Romans was also one of the twelve.
The work of the resurrected Christ continues. Who's sleeping on the job? Who is betraying the message?