NEW: Community on "heightened alert" following killings, county judge Bruce Wood says NEW: Judges, others following security protocols recommended by authorities, Wood says Kaufman County District Attorney Mike McLelland and wife found dead in their home Two months earlier, assistant district attorney shot to death outside county courthouse Kaufman County, Texas (CNN) -- Frayed nerves and a palpable tension cloak this quiet Texas county as half a dozen agencies hunt for the killer or killers apparently bent on taking out top criminal justice officials. The killings have residents and prosecutors in Kaufman County, about 50 miles east of Dallas, on edge -- and on guard. We are all on heightened alert. There's no question about that," county Judge Bruce Wood told CNN's "Starting Point" on Monday, a few hours before the county courthouse was scheduled to reopen under heavy security. The district attorney's office, however, will remain closed Monday amid an intensive investigation and lingering questions over what's happening: Are the killings the work of a lone wolf or a gang? Wood, who is not involved in the investigation and does not handle criminal cases in the county, earlier said he believes there is a "strong connection" between the McLellands' deaths and the slaying of Assistant District Attorney Mark Hasse, who was killed January 31. The two prosecutors "worked on similar cases very closely," he said. "The folks who work in the courthouse, they've been through a lot," Wood said. Investigators at the McLellands' home recovered several shell casings from a .223-caliber rifle, a law enforcement source said Sunday. The Kaufman County Sheriff's Office won't officially say whether the killings are connected. But some speculate white supremacists targeted by state and federal law enforcement may have played a role. McLelland, in an interview with The Associated Press after Hasse's death, had raised the possibility that Hasse was killed by a white supremacist gang. "We put some real dents in the Aryan Brotherhood around here in the past year," McLelland told the news agency. In November, a federal grand jury in Houston indicted 34 alleged members of the Aryan Brotherhood of Texas -- including four of its senior leaders -- on racketeering charges. Multiple agencies investigated the case, including officials from the Kaufman County district attorney's office. At the time, Assistant U.S. Attorney Lanny A. Breurer 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." Weeks later, the Texas Department of Public Safety issued a statewide warning saying it had "credible information" that members of the Aryan Brotherhood were planning to retaliate. In the AP interview, McLelland said Hasse had not prosecuted cases against such gangs, but his office handled several. In the same interview, McLelland told the AP he began carrying a gun after Hasse's death and was answering his door more carefully. Shock waves through the community Wood said the courthouse will be well-protected when it reopens Monday and said court officials are following law enforcement directions designed to keep them safe both on and off the job. Sheriff David Byrnes was similarly tight-lipped: "We are taking precautions to protect other elected officials in the county." Attorney Pete Schulte, who has worked in the community, said the killings have left the community in shock. "The law enforcement community here is very uncomfortable," he said. It's really sending some shock waves through the community. Colorado killing McClelland's death came 11 days after the similar shooting death of Colorado prisons chief Tom Clements -- shot to death March 19 after he answered the door at his home. 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. An FBI spokesman said the Denver field office was not involved in Kaufman County case. McLelland never said he was worried, even after his deputy's death, Wood said. Before his death, McLelland called Hasse "a stellar prosecutor" who knew that threats were part of the job.