Two years ago this week, Folsom State Prison inmates Michael Vera and Cameron Welch allegedly cut the throat of another prisoner at the command of prison gang leader Samuel Cox.
Four months later, according to court records, guards at Corcoran State Prison pepper-sprayed a mentally ill inmate while other guards watched and made video recordings.
In both cases, guards were accused of failing to report the violations.
In a California Office of the Inspector General report released in June, investigators talk about a practice of guards failing to report the violations and crimes they witness. It's referred to as a "code of silence" among guards.
In one case, the report stated two correctional officers allegedly stopped speaking to a sergeant who previously reported misconduct of team members. It says the guards called the sergeant a "rat."
Former correctional officer and union representative Jeff Doyle said, "That is what it really comes down to is not being a tattle-tale, not a rat."
Doyle, who now operates a prison employee blog titled Paco Villa, said 99 percent of guards are honest.
"The code of silence thing was really at its height when I first started doing the blog, and it's one reason the blog took off and became a success," Doyle said.
In the case of the murdered inmate at Folsom Prison, former guard Nader Hamameh allegedly did not report inmate Richard Leonard was about to be attacked even after another prisoner warned him.
Records show Hamameh was also reprimanded for bringing in a box cutter and eight razors in 2009.
Hamameh and his attorney declined to comment for this story.
The California Department of Corrections and Rehabilitation would not comment on Hamameh because he is currently suing the agency for firing him.
But speaking about the "code of silence" in general, the department released this statement:
The California Department of Corrections and Rehabilitation has a zero tolerance policy for any form of dishonesty, retaliation, or "Code of Silence" act. CDCR employees consistently receive "Code of Ethics" training regarding their responsibilities to recognize and report any "Code of Silence" act which may have occurred. All reports of dishonesty or behavior in relation to any forms of "Code of Silence" are investigated thoroughly.
A former corrections administrator who served as the chief deputy warden at Salinas Valley Prison for 32 years and who is now a prison consultant said training alone is not enough.
"Correctional officers can be manipulated by inmates," Edward Caden said. "Once you've compromised that officer's integrity, you own them. That type of compromising can lead to requesting them to introduce drugs and the blackmail that if you don't do it, I will turn you in for these other offenses that I know you've committed."
Doyle said guards are like cops. They have to watch out for one another.
"It's us and them in there," he said, adding, "It's a matter of self-preservation for a lot of these guys."
The Office of the Inspector General said in its report it will continue to monitor the "code of silence" problem and other issues inside the prison system.