Are killings retribution?
Authorities insist that they just don't know who may be behind the killings.
However, McLelland's office was one of numerous Texas and federal agencies involved in a multiple-year investigation that led to the 2012 indictment of 34 alleged members of the Aryan Brotherhood of Texas, including four of its senior leaders, on racketeering charges.
At the time, Assistant U.S. Attorney Lanny A. Breuer called the indictment a "devastating blow" to the organization, which he said used threats and violence, including murder, against "those who violate (its) rules or pose a threat to the enterprise."
The FBI describes the group as a "whites only," prison-based gang with members operating inside and outside of state and federal prisons throughout Texas and elsewhere in the United States since at least the early 1980s."
While authorities have not said whether they have established a link between the deaths of Hasse and McLelland, or the involvement of white supremacists, Texas law enforcement agencies did warn shortly after the November 2012 indictment that there was "credible information" that members of the Aryan Brotherhood were planning to retaliate" for the indictment.
Wood said Monday that no physical evidence links McLelland's death and Hasse's, although previously he had said he believes there is a "strong connection" between the killings.
In an interview with The Associated Press after Hasse's death, McLelland said his deputy hadn't been involved in the Aryan Brotherhood of Texas investigation. But the district attorney nevertheless raised the possibility the group was behind his death.
"We put some real dents in the Aryan Brotherhood around here in the past year," McLelland told the news agency.
In the AP interview, McLelland said he, too, began carrying a gun after Hasse's death and was answering his door more carefully.
Pete Schulte, a criminal defense attorney who has worked in the county, said other lawyers and public servants were nervous.
"Having that type of environment going on where people who are just doing their jobs (and) getting assassinated -- this is what this is, elected officials getting assassinated -- and that is sending a chill through the (legal) community and the community in general," he said.
Schulte speculated that the killings were "personal."
"If this was a case that somebody was trying to change, they would have been going after witnesses and not the prosecuting attorney," he said.
As if the potential links between Hasse and McLelland's shootings weren't enough, speculation has also extended to whether the shootings have any connection to the March 19 death of Colorado prisons chief Tom Clements, who was gunned down after answering the door to his house.
While authorities have offered no suggestion the crimes are linked, the man suspected of killing Clements was once a member of a white supremacist group, the 211 Crew. That man, Evan Ebel, died in a shootout with sheriff's deputies in northern Texas.
The white supremacist angle is just one of many possibilities, the Dallas Morning News quoted McLelland's former boss in the Dallas public defender's office as saying.
"It could be local meth lab people down there in Kaufman County, it could be Mexican cartel, it could be the Aryan Brotherhood," the newspaper quoted Former Dallas Chief Public Defender Brad Lollar as saying. "Or it could just be someone with a personal grudge."
On heightened alert
The federal Bureau of Alcohol, Tobacco, Firearms and Explosives joined Texas Rangers, the FBI and local authorities in investigating the killing of McLelland and his wife, the agency's Dallas office spokesman, Andrew Young, told CNN.
Several dozen FBI agents and support staff are now assisting the investigation, said Katherine Chaumont, a spokeswoman for the bureau's Dallas field office.
In Houston, Harris County Sheriff Adrian Garcia put District Attorney Mike Anderson and his family under 24-hour security, said Sara Marie Kinney, a spokeswoman for the prosecutor's office. Anderson's office was part of the same task force as Kaufman County authorities.
Mayor Fortner said Monday on CNN's Starting Point the fear is pervasive.