Dear student
Evan's cell had been bugged because, Evan had tried to escape from prison several times and the governor was sure he was going to try to do it once again. By listening in on Evan's conversation, he could hear anything that Evan did or said, meaning that it would be impossible for Evan to escape. The second reason was for the safety of the Reverend Stuart McLeery. The Governor wanted to make sure that Evan didn't hurt the reverend and if anything happened, he would know when he heard it.
Regards