Updated at 4:00 p.m. ET
In the wake of the weekend slayings of a Texas district attorney and his wife that prompted investigators to suspect a violent white supremacist prison gang, an assistant U.S. attorney in Houston has withdrawn from a large racketeering case against the Aryan Brotherhood of Texas, CBS News correspondent Anna Werner reports from Kaufman, Texas.
Richard O. Ely II, a Houston defense attorney for one of the 34 defendants, told The Dallas Morning News that Assistant U.S. Attorney Jay Hileman sent him an email on Tuesday informing him that he was off the case.
"I understand why someone would want to step back," Ely told Houston television station KTRK-TV. "It makes sense to me, especially people that have families."
Ely told the newspaper another Justice Department prosecutor, from Washington, D.C., will be assigned to the case to replace Hileman. The replacement would join David Karpel, a lawyer with the Justice Department's gang unit, who is also assigned to the case. Ely said the case will continue to be prosecuted in Houston.
Angela Dodge, a spokeswoman for the U.S. attorney's office in Houston, didn't confirm or deny to the newspaper that Hileman was off the case.
The gang was the focus of a December law enforcement bulletin warning that its members might try to attack police or prosecutors.
The weekend deaths of Kaufman County District Attorney Mike McLelland and his wife, who were found fatally shot in their home, were especially jarring because they happened just two months after one of the county's assistant district attorneys, Mark Hasse, was killed near his courthouse office.
A sheriff's official said a man has been arrested for making a threat during the investigation into the killings, but there is no indication he's connected to the deaths. Kaufman County sheriff's Lt. Justin Lewis said Wednesday that 56-year-old Nick Morale has been arrested on a charge of making a terroristic threat.
Lewis said Morale called the tip line established by authorities after the killings of McLelland and his wife Cynthia and used it to threaten a specific county official. Lewis says there's nothing to link Morale to the McLellands' deaths or the killing of Hasse and he's not a suspect in either case.
Separately, the Los Angeles Times reports investigators have "turned their attention to a former local official who threatened (McLelland and Hasse) after losing his job in a corruption investigation, according to federal law enforcement officials briefed about the case."
The Times cites federal officials as saying the man who emerged as a person of interest this week was convicted and placed on probation for stealing public property in Kaufman County two years ago.
"After his arrest," the newspaper says, "investigators found he had numerous guns, including an assault rifle and survivalist equipment, one of the federal officials said. The officials declined to be identified, citing the ongoing investigation."
Efforts to reach a plea fell apart, and the man threatened retaliation against the two prosecutors, another federal official said. He had also threatened to burn down the home of a local lawyer.
The attorney for the person of interest said he had "strenuously denied making any threats."
Meanwhile, The New York Times reports that officials were investigating a Facebook posting from a man who identified himself as a resident of Kaufman County.
According to the Times, the person wrote on the social networking site Monday that the killings were "acts of revenge against the tyrannical, unjust, Pit Bull style treatment of every poor soul damned to do business in the Kaufman County courthouse."
The writer mentioned another Kaufman prosecutor, saying that official "will soon perish, bringing closure to an era of unacceptable practices and allowing Kaufman County residents to move forward with liberty and justice," according to the Times.
A spokeswoman for the FBI's Dallas office told the Times that she couldn't comment on specific leads.
The Aryan Brotherhood of Texas has been in the state's prison system since the 1980s, when it began as a white supremacist gang that protected its members and ran illegal activities, including drug distribution, according to Terry Pelz, a former Texas prison warden and expert on the gang.
The group, which has a long history of violence and retribution, is now believed to have more than 4,000 members in and out of prison who deal in a variety of criminal enterprises, including prostitution, robbery and murder.
It has a paramilitary structure with five factions around the state, Pelz said. Each faction has a general, who is part of a steering committee known as the "Wheel," which controls all criminal aspects of the gang, according to court papers.
Four top leaders of the group were indicted in October for crimes ranging from murder to drug trafficking. Two months later, authorities issued the bulletin warning that the gang might try to retaliate against law enforcement for the investigation that also led to the arrest of 30 other members.
At the time, prosecutors called the indictments "a devastating blow to the leadership" of the gang. Pelz said the indictments might have fragmented the gang's leadership.
Hasse's death on Jan. 31 came the same day as the first guilty pleas were entered in the indictment. No arrests have been made in his killing.
McLelland was part of a multi-agency task force that investigated the Aryan Brotherhood with help from the FBI, the Drug Enforcement Administration and police in Houston and Fort Worth. McLelland and his wife, Cynthia, were found shot to death Saturday in their rural home just outside the town of Forney, about 20 miles from Dallas.
Detectives have declined to say if the Aryan Brotherhood is the focus of their investigation, but the state Department of Public Safety bulletin warned that the group is "involved in issuing orders to inflict 'mass casualties or death' to law enforcement officials involved in the recent case."
Killing law enforcement representatives would be uncharacteristic of the group, Pelz said.
"They don't go around killing officials," he said. "They don't draw heat upon themselves."
But Pelz, who worked in the Texas prison system for 21 years, said the gang has a history of threatening officials and of killing its own members or rivals.
The 18-count indictment accused gang members of being involved in three murders of rival gang members, multiple attempted murders, kidnappings, assaults and conspiracy to distribute methamphetamine and cocaine.
Some of the attempted murders in the indictment involved gang members who were targeted for not following orders or rules or who were believed to be cooperating with law enforcement. The indictment also alleges that gang members discussed killing a police officer in 2008 and allegedly ordered a subordinate gang member to kill a prospect "and to return the victim's severed finger as a trophy."