After three mysterious killings of law enforcement officials, including two Texas prosecutors and Colorado’s chief of prisons, authorities have provided little information about who they think is responsible or whether the cases are even connected. Many are speculating that the Aryan Brotherhood of Texas, a prison gang, may be involved, the Associated Press reports:

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. . .

The group 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.

The U.S. Department of Justice charged 34 of its members on Nov. 9 with a range of crimes, including four of the organization’s leaders. Law enforcement officers arrested 14 of those charged that day. Another 15 were already in custody, and five remained at large.

Mike McLelland, the district attorney in Kaufman, Texas, and his wife were found dead in their home on Saturday, according to the Associated Press:

The slayings came less than two weeks after Colorado’s prison chief was shot to death at his front door, apparently by an ex-convict, and a couple of months after Kaufman County Assistant District Attorney Mark Hasse was killed in a parking lot a block from his courthouse office. No arrests have been made in Hasse’s slaying Jan. 31. . . .

Colorado’s corrections director, Tom Clements, was killed March 19 when he answered the doorbell at his home outside Colorado Springs. Evan Spencer Ebel, a white supremacist and former Colorado inmate suspected of shooting Clements, died in a shootout with Texas deputies two days later about 100 miles from Kaufman. (Read the full article here.)

After the shootout, deputies found materials for making a bomb in Ebel’s car. Colorado authorities later said he had been released early from prison there due to a clerical error. Ebel had been held in solitary confinement in Colorado, the Associated Press noted:

A darkly ironic connection emerged among Ebel, Clements and Colorado Gov. John Hickenlooper when the governor confirmed Friday he was a longtime friend of Ebel’s father, attorney Jack Ebel.

Jack Ebel had testified before Colorado lawmakers two years ago that solitary confinement in a Colorado prison was destroying his son’s psyche.

When Hickenlooper interviewed Clements for the top prison job in Colorado, he mentioned the case as an example of why the prison system needed reform, but Hickenlooper said he did not mention Ebel by name. Later, Clements eased the use of solitary confinement in Colorado and tried to make it easier for people held there to re-enter society.

Murders of prosecutors are rare. Here is a review of the cases of 14 prosecutors who have been killed.