Albert Barnes Commentary Mark 1:23

"And straightway there was in their synagogue a man with an unclean spirit; and he cried out," — Mark 1:23 (ASV)

A man with an unclean spirit. See Matthew 4:24. It is probable that this man had lucid intervals, or he would not have been admitted into the synagogue. While there, one of his fits came on, and he suddenly cried out.