SANTA ANA, Calif. (AP) — The American Civil Liberties Union has filed a lawsuit over the jailhouse informant scandal that has upended more than a dozen criminal cases in Southern California.

The suit announced Wednesday claims the Orange County district attorney's office and the sheriff's department engaged in an elaborate scheme to violate defendants' constitutional rights through a secret network of jailhouse snitches.

The complaint also claims that the district attorney's office illegally withheld information about the informants from defense attorneys.

The allegations led to mass killer Scott Dekraai avoiding the death penalty.

District Attorney Tony Rackauckas and Sheriff Sandra Hutchens have denied systemic misuse of jailhouse informants.

A DA's office statement says it hasn't been served with the lawsuit but says use of informants has been consistently upheld by the U.S. Supreme Court.