A man accused of shooting a Rusk County deputy to death has entered a plea of not guilty.  Doug Nitek withdrew a mental insanity plea during a Monday hearing in northwestern Wisconsin.  Nitek also withdrew his motion requesting a change of venue.  The defense had originally argued the move out of the county would be required if a non-biased jury was to be seated.  A follow-up to deal with several issues has been scheduled for June 4th in St. Croix County.  A September trial date has been set for Nitek.