Accused Minnesota assassin Vance Boelter's alleged plan to kill more politicians on his target list was foiled by a police sergeant's proactive hunch, and his capture came after he made a big misstep that exposed his whereabouts to an eagle-eyed neighbor, authorities said.

Authorities detained the wife of 57-year-old Vance Boelter, the suspect accused in the deadly shooting of a Minnesota state lawmaker and her husband early Saturday morning.

Minnesota state Rep. Melissa Hortman (D) and her spouse were fatally shot, while state Sen. John Hoffman (D) and his wife were wounded, police said