Prosecutors are still trying to figure out who was behind the ambush assassination of a Texas prosecutor, and one of his recent cases stands out for who was the focus:

The prosecutor, Mark E. Hasse, worked in the Kaufman County district attorney’s office in Kaufman, a town of 6,800 people about 35 miles from Dallas. He was shot several times shortly before 9 a.m. as he walked in an employee parking lot about a block from the courthouse.

The authorities said the suspect or suspects got out of a Ford Taurus, opened fire on Mr. Hasse and then returned to the car and drove away. Investigators were trying to determine why Mr. Hasse was targeted and if the shooting had anything to do with cases he had prosecuted.

“I’ve been doing this 43 years, and I’ve never seen anything like this,” said David A. Byrnes, the Kaufman County sheriff.

Mr. Hasse, 57, was the county’s lead felony prosecutor and a well-respected assistant district attorney. He received his law degree from Southern Methodist University in Dallas and in the 1980s served as a prosecutor in the Dallas County district attorney’s office, where he had been the chief of the organized-crime section.

Kaufman County prosecutors have been involved in investigations of the Aryan Brotherhood of Texas prison gang. In November, federal officials in Houston thanked a number of local agencies for their work — including Kaufman County prosecutors — when more than 30 senior leaders and other members of the gang were indicted on federal racketeering charges.

Officials said they were reviewing Mr. Hasse’s current cases — as many as 400 of them — and previous ones for leads.

Lawyers and prosecutors throughout North Texas were stunned by the attack. The Dallas County district attorney, Craig Watkins, sent an e-mail encouraging his employees to exercise caution.

The SPLC notes that the Aryan Brotherhood in Prison is one of the largest and most dangerous gangs operating in prisons across the nation. But it’s not a hate group in the traditional sense either, as they’ll do business with whoever they think will help them gain power, even if means working with the likes of Mexican drug cartels.