Shortly after the high-profile murders of several Colorado and Texas prison officials, possibly at the hands of white supremacist groups, Assistant U.S. Attorney Jay Hileman has withdrawn from prosecuting a large racketeering case against the Aryan Brotherhood of Texas. Hileman reportedly resigned due to fears about security. 

According to Talking Points Memo, Hileman emailed every lawyer involved in the Aryan Brotherhood’s defense to state that he was concerned about security and he would be withdrawing from the prosecution team. 

"He sent the email to every lawyer representing a defendant in the Aryan Brotherhood federal case, and he said -- very short email -- that he was withdrawing for security reasons," Houston attorney Katherine Scardino told TPM on Tuesday. 

Scardino represents Aryan Brotherhood “general” Terry Sillers, who has agreed to plea guilty in the case. Due to security concerns about Aryan Brotherhood retaliation, Sillers, who will not be prosecuted until he testifies in other cases, is being held at a secure location unknown from even his lawyer. 

"I don't know where Mr. Sillers is, he's under protective custody," Scardino said. "And I don't really want to know."

Soon after Talking Points Memo posted their report, the Dallas News Crime Blog confirmed that Hileman did indeed withdraw over security concerns, stating that another, unnamed federal prosecutor from Washington will take over Hileman’s place.

In the past few weeks, three law enforcement officials have been killed, with white supremacist group members as the main suspects. On March 20, Colorado prison director Tom Clements was shot to death at his home. The prime suspect is 211 Crew member Evan Ebel, who was killed in a shootout with Texas police after a warrant was issued for his arrest.

In addition to Ebel’s slaying of Clements, Kaufman County, Texas, District Attorney Mike McLelland and his wife, Cynthia, were found slain in their home Saturday. McLelland's assistant Mark Hasse was also murdered in a parking lot two months earlier. No suspects have been named in the murders, but the officials are suspected to have been killed by members of the Aryan Brotherhood of Texas, according to CBS News

Ebel’s 211 Crew, also known as the Brotherhood of Aryan Alliance, is not formally connected to the Aryan Brotherhood, which has its hands in criminal activities ranging from drug trafficking to extortion. However, Slate theorizes that due to the close timings and retaliatory nature of the three killings, the white supremacist gangs may in fact be part of a multifaceted attack on prison officials across state lines.