Two federal deputy marshals arrested Lois Riess, 56, about 8:30 p.m. at a South Padre Island, Texas, restaurant, the U.S. Marshals Service said in a statement.
Police say Lois Reiss killed her husband in one part of the country, then killed a woman nearly 1,700 miles away.
Watch the video to see the deadly path of suspected "smiling grandma."