A prison guard stands on a tower at the Connally Unit near Kenedy, Texas, after an inmate escape in 2001. AP Photo/Eric Gay The recent assassinations of two Texas prosecutors have drawn attention to brutal gangs that rule prisons in the Lone Star State and beyond.

The Aryan Brotherhood of Texas (ABT) was linked to the case after the gang allegedly issued orders to inflict revenge on law enforcement for recent arrests.

The ABT and similar gangs allegedly operate criminal enterprises involving meth trafficking and murder even though many of their members are behind bars.

To do so, gang members send coded messages to each other through girlfriends on the outside, former Texas prison warden Terry Pelz tells us. Prison gangsters also rely on the very people guarding them to facilitate their criminal activities, according to Pelz, who's now a "prison environment" expert and consultant.

Prison guards have been known to accept bribes in exchange for bringing in contraband like cellphones or drugs. Since guards listen in on prisoners' official phone calls, a cellphone can be highly useful contraband.

Even though this contraband can play a huge role in making prison gangs' illegal activities possible, Pelz says, corrections officers sometimes just get fired and not criminally prosecuted if they get caught.

But in February prosecutors handed down a rare federal indictment accusing 13 Texas Department of Criminal Justice prison guards of racketeering. The feds said they were cracking down on a Beeville, Texas facility's "culture of corruption" that involved smuggling phones in to members of the Aryan Circle (a rival of the Aryan Brotherhood of Texas).

One of the former corrections officers, 38-year-old Jaime Jorge Garza, pleaded guilty after getting caught at a checkpoint with four cellphones, pot, and tobacco, the Corpus Christi Caller-Times reported earlier this month. In court, Garza said he got pushed around a lot when he was a corrections officer.

“When I got caught at the checkpoint I was relieved," he said, according to the Caller-Times. "I was glad it was over.”

Not only is it tempting for low-paid guards to accept bribes in the first place, but it's hard for them to stop doing so because prison gang members might threaten them, says Pelz, who was a warden in an Angleton, Texas prison in the 1980s when the Aryan Brotherhood of Texas started to proliferate.

"Our standards aren't very high for hiring officers," Pelz says. "These youngsters come to work for the penitentiary and the convicts eat them alive."