Mid-morning Monday, at the end of North Seventh Street in Surf City, the choppy water of Manahawkin Bay churned relentlessly in front of a vacant two-story, single-family home with a real estate for sale sign in the yard. Construction vehicles dotted the otherwise quiet street, a contrast to the police activity a week prior after a longtime couple was found stabbed to death in the bayfront home.

Borough police discovered the bodies of John “Jack” Enders, 87, and Francoise “Frenchie” Pitoy, 75, on the afternoon of…