Ashley Bortner's burned body was found earlier this month near railroad tracks in Massachusetts.
Police want to talk to Fernando Owens in the death of Bortner, 29. Family members said she had been living in Boston's Hyde Park neighborhood.
Prosecutors said Owens' son was shot to death on Nov. 2. The next day, Bortner's body was found, gagged, bound, and burned.
Police received a 911 call earlier this month about a suspicious vehicle in Bridgewater, Mass., about 25 miles south of Boston. The caller said two people were also seen in the area.
Arriving officers discovered a fire burning in a vehicle parked near the tracks, and determined that it was a human body, later identified as Bortner.
Plymouth District Attorney Timothy Cruz said at the time that it appears she was targeted and her death was not random.