(CNN) -- As investigators scramble to figure out who killed two Texas prosecutors, suspicions abound over whether the Aryan Brotherhood of Texas played a role.
Authorities have not officially linked the two slayings, nor do they know whether the white supremacist group ordered the attacks.
But a series of events leading up to the killings have raised questions about the group's possible involvement.
Here's a primer on the Aryan Brotherhood of Texas:
What is the Aryan Brotherhood of Texas?
The FBI describes the group as a "whites only," prison-based gang that has been operating since at least the 1980s.
"I think the Aryan Brotherhood of Texas today is arguably the most violent white supremacist prison gang out there," said Mark Potok of the Southern Poverty Law Center.
The group has been blamed for more than 100 homicides and at least 10 kidnappings since the early 1980s.
Is the Aryan Brotherhood of Texas part of the Aryan Brotherhood?
Inmates in Texas asked the Aryan Brotherhood, a California-based prison gang, for permission to start a Texas chapter, but they were denied membership, the Southern Poverty Law Center said. It's not clear why.
Nonetheless, the Texas-based group modeled itself after the California gang.
What does the Aryan Brotherhood of Texas stand for?
Like the Aryan Brotherhood, the Texas group's main purpose morphed from protecting white inmates to criminal activities involving drugs, extortion and murders, authorities say. It also espouses a white supremacist ideology.
"At the end of the day, these organizations are really fundamentally criminal enterprises," Potok said. "That means, above all, their interest is in green. In money. Skin color comes long after that."
Its reach began to extend outside prison walls as more members finished their sentences. ABT members on parole are required not only to remain loyal to the gang, but also to recruit new members.
"Brutal beatings, fire bombings, drug trafficking and murder are all part of ABT's alleged standard operating procedures," said Lanny Breuer, a former Assistant U.S. Attorney General.
Did the group play a role in the deaths of Kaufman County District Attorney Mike McLelland and Assistant District Attorney Mark Hasse?
Authorities don't know.
But McLelland's office was one of numerous agencies involved in a multi-year investigation that led to the indictment of 34 alleged members of the ABT -- including four of its senior leaders -- on racketeering charges in November.
At the time, Breuer called the indictment a "devastating blow" to the organization.
Weeks later, the Texas Department of Public Safety issued a statewide warning saying it had "credible information" that members of the group were planning to retaliate.
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 the death.
"We put some real dents in the Aryan Brotherhood around here in the past year," McLelland told the news agency.
How do members join the Aryan Brotherhood of Texas?
"It is said to be one of the gangs that live by the 'blood-in, blood-out' code, meaning that you can only get into ABT by carrying out some kind of attack," Potok said. "And similarly ... you can only leave in a body bag."
CNN's Ed Lavandera contributed to this report.