Updated March 31,2013, 12:31 AM ET
KAUFMAN, Texas A North Texas county district attorney and his wife were found dead in their home Saturday, two months after one of his assistant district attorneys was shot to death in a parking lot a block from his office.
Police, FBI agents and Kaufman County sheriff's deputies were investigating the deaths of county District Attorney Mike McLelland and his wife, Cynthia, sheriff's Lt. Justin Lewis said late Saturday. CBS Station KTVT Dallas reported that security is being increased involving all Kaufman County officials.
Lewis said he couldn't discuss the investigation in further detail, including the nature of the couple's deaths and whether authorities believe it is linked to the Jan. 31 fatal shooting of an assistant Kaufman County district attorney, Mark Hasse.
KTVT also reported that the McLellands have five children, including a son who is a Dallas police officer.
The Dallas Morning News reported that Police Chief Chris Aulbaugh said the McLellands had been shot in their home and that although investigators didn't know if their deaths and Hasse's were related, they couldn't discount it.
"It is a shock," Aulbaugh said late Saturday, the paper reported. "It was a shock with Mark Hasse, and now you can just imagine the double shock and until we know what happened, I really can't confirm that it's related but you always have to assume until it's proven otherwise."
Sam Rosander, who lives in the same unincorporated area of Kaufman County as the McLellands, told The Associated Press that sheriff's deputies were parked in the district attorney's driveway for about a month after Hasse was killed.
Aulbaugh said recently that the FBI was checking to see if Hasse's killing could be related to the killing of the head of Colorado's prison system, Tom Clements, who was gunned down after answering the doorbell at his home.
Evan Spencer Ebel, a former Colorado inmate and white supremacist who authorities believe killed Clements, was gunned down in a March 21 shootout with Texas deputies about 100 miles from Kaufman.
Aulbaugh said at the time that the investigation into whether the cases were linked was routine for attacks that appear similar. Both targeted law enforcement officials. Authorities have investigated whether Hasse's death could be linked to a white supremacist gang.
Aulbaugh had said there's no indication that Hasse, 57, had been afraid he might be killed and, although the prosecutor was a licensed peace officer, officials refused to say whether he was carrying a weapon.
Hasse was chief of the organized crime unit when he was an assistant prosecutor in Dallas County in the 1980s, and he handled similar cases in Kaufman County, 33 miles southeast of Dallas.
McLelland had said Hasse was one of 12 attorneys on his staff, all of whom handle hundreds of cases at a time.
"Anything anybody can think of, we're looking through," McLelland said after the assistant prosecutor was killed.
In recent years, Hasse played major roles in Kaufman County's most high-profile cases, including one in which a justice of the peace was convicted on theft and burglary charges and another in which a man was convicted of killing his former girlfriend and her 10-year-old daughter.