The fugitive accused of stabbing an elderly Massachusetts couple to death after an argument over a barking dog was captured in Florida, cops announced. Christopher Keeley, 27, was arrested Thursday at 8:20 p.m. in Miami Beach, over 1,500 miles from where he allegedly bludgeoned Carl and Vicki Mattson, both 70, in their Marshfield home, the Plymouth County District Attorney’s Office said. Police believe Keeley killed the couple after an argument over a barking dog.