The DA’s office said Christopher Keeley, 27, from Weymouth, was arrested in Miami Beach Friday night.
Keeley is accused of stabbing and killing Carl Mattson and Vicki Mattson. Both were found dead in their home on Gotham Hill Drive around 9:30 p.m. Tuesday.
Their missing dog was also found dead inside the home.
The DA’s office also believes this was not a random act of violence and that the victims were targeted.
Keeley is expected to attend a hearing in Florida before returning to Massachusetts to face charges.