Yes, Hutch was killed by the coven. Guy, Rosemary’s husband, came home unexpectedly from rehearsal when Hutch was visiting with Rosemary and Hutch seemed to be catching on to what was going on. When Hutch was leaving he was missing a glove, which Guy had taken to give to the coven to cause Hutch’s demise just as Guy had taken the tie of the man whose part he wanted to get that caused the man to go blind.
What I never understood was why the coven could not recruit a willing young woman to mate with the devil and bear the child. Surely they could have found somebody in the world besides the women they had to dupe.
Also, why did Frank Sinatra marry Mia Farrow? I never understood that either.