John DeRoche never knew Philip Scott Fournier had confessed to anyone but him when the Bangor High School janitor took the stand last month in the Joyce McLain murder trial. It wasn’t until he saw news reports about that day’s testimony that DeRoche, 78, of Bangor learned that Fournier’s off-handed confession to him in 1989 confirmed statements he’d made about killing McLain eight years earlier to his minister, the Rev.