Deputies have yet to confirm a motive in the killing of Kaufman County District Attorney Mike McLelland and his wife Cynthia.
The news of their death came less than two weeks after Colorado's prison chief was gunned down at his front door by a white-supremacist ex-convict, and two months after McLelland's assistant district attorney, Mark Hasse, was shot to death in a parking lot a block from his office Jan. 31.
After his assistant prosecutor was assassinated, McLelland felt on edge and warned his employees to be on alert. The 63-year-old reportedly carried a gun everywhere he went.
On Saturday, he and his wife were found dead in their home just outside the town of Forney, about 20 miles from Dallas.
Authorities have not confirmed whether their deaths were linked or related to the other assassinations but the possibility has not been discounted.
"Everybody's a little on edge and a little shocked," Forney Mayor Darren Rozell said. "It appears this was not a random act."
McLelland himself, in an Associated Press interview, raised the possibility that Hasse was gunned down by a white supremacist gang. McLelland, elected DA in 2010, said that Hasse hadn't prosecuted any cases against white supremacists but that his office had handled several, and those gangs had a strong presence in the area.
"We put some real dents in the Aryan Brotherhood around here in the past year," McLelland said after Colorado's corrections director, Tom Clements, was shot to death March 19 when he answered the doorbell.
The FBI and the Texas Rangers have joined the investigation into the McLellands' deaths.
The Associated Press contributed to this report.