Three prison inmates are facing additional life sentences after a Kern County...

Three prison inmates are facing additional life sentences after a Kern County Jury returned a guilty verdict in a prison assault case.

Joshua Diaz (37), Derek Sommer (38), and Mario Lopez (36) were convicted yesterday of Attempted Murder. Additionally, Joshua Diaz and Derek Sommer were found guilty of Assault by a Life Prisoner. The jury also found it true that the defendants caused great bodily injury to the victim.

The case was prosecuted by Deputy DA Victor Ghaly.

On April 23, 2020, Diaz, Sommer, and Lopez were inmates at Kern Valley State Prison (KVSP) in Delano. While the defendants were on the exercise yard, they obtained inmate manufactured weapons and approached the victim inmate. All three defendants stabbed the victim multiple times in the face and upper torso area. The victim suffered a lacerated liver, required a chest tube to breathe, a lacerated bowel, a life-threatening laceration to the head, and numerous other puncture wounds. As officers approached the scene to break up the attack, Lopez fled. Inmates Sommer and Diaz knocked the victim to the ground and continued to stab him. The victim attempted to block the strikes, but was unable to prevent the attack.

All three defendants were housed at KVSP in Delano for convictions originating outside of Kern County. • Sommer is currently serving a sentence of 140 years to life from Los Angeles County for five counts of attempted murder. • Diaz was convicted in San Diego County of torture and false imprisonment and is serving a sentence of 15 years to life. • Lopez is serving a 25-year sentence for carjacking and assault with a deadly weapon, stemming from a conviction in Los Angeles County.

DA Zimmer commented; “The rule of law does not stop at the prison walls; when inmates continue to engage in unlawful violence while in custody, successful prosecutions extend their sentences to ensure they are not allowed to threaten public safety again.”

Sentencing is set for May 28, 2026. Inmates Diaz and Sommer are facing an additional 27 years to life for their most recent conviction, while inmate Lopez faces an additional 25 year to life sentence.