Complex sentence: The police think there is a maniac killer on the loose--but, as Peterson's boss points out, Gramps'.30 -.30 got off 4 shots "and" Ed Blackburn was a crack shot.
Split into simpler sentences: The police think there is a maniac killer on the loose. But, as Peterson's boss points out, Gramps' 30-30 got off 4 shots "and" Ed Blackburn was a crack shot.