On Saturday, he and his wife were found dead in their home just outside the town of Forney, about 20 miles from Dallas, killed in an attack for which authorities have given no motive.
"Everybody's a little on edge and a little shocked," Forney Mayor Darren Rozell said. "It appears this was not a random act."
The killings 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 Kaufman County Assistant District Attorney Mark Hasse was shot to death in a parking lot a block from his office Jan. 31. No arrests have been made in Hasse's slaying.
Kaufman County Sheriff David Byrnes confirmed Sunday that the McLellands had been shot. As for whether their deaths were related to Hasse's slaying, Byrnes said there was nothing to indicate that "for sure," but declined to discuss it further during a news conference.
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.
Kaufman Police Chief Chris Aulbaugh said recently the FBI was checking to see if Hasse's killing could be related to Clements'. Evan Spencer Ebel, a former Colorado inmate and white supremacist who authorities believe killed Clements, died in a March 21 shootout with Texas deputies about 100 miles from Kaufman.
Investigators had been looking into the possible involvement of the Aryan Brotherhood of Texas in Hasse's killing.
McLelland, 63, said after Hasse's slaying that he carried a gun everywhere he went, even to walk his dog. He figured that was where assassins were more likely to try to get him. He said he had warned all his employees to be constantly on the alert.
"The people in my line of work are going to have to get better at it," he said of the danger, "because they're going to need it more in the future."
The number of attacks on prosecutors, judges and senior law enforcement officers in the U.S. has spiked in the past three years, according to Glenn McGovern, an investigator with the Santa Clara County, Calif., District Attorney's Office who tracks such cases.
But they're still rare. McLelland is the 13th prosecutor in the U.S. that the National Association of District Attorneys has recorded killed since the organization began keeping track in the 1960s.
For about a month after Hasse's slaying, sheriff's deputies were parked in the district attorney's driveway, said Sam Rosander, a McLelland neighbor.
The FBI and the Texas Rangers joined the investigation into the McLellands' deaths.
McLelland and his wife, Cynthia, were the parents of two daughters and three sons. One son is a police officer in Dallas. The couple had moved into the home a few years ago, Rozell said.
"Real friendly, became part of our community quickly," Rozell said. "They were a really pleasant happy couple."
Associated Press writers Michael Graczyk in Houston, Angela K. Brown in Fort Worth and Peter Banda and Nicholas Riccardi in Denver contributed to this report.
Additional reporting by TPM.