Three prison inmates have been convicted of attempted murder in a violent assault at Kern Valley State Prison and now face additional life sentences, prosecutors said.

A Kern County jury on Wednesday found Joshua Diaz, 37, Derek Sommer, 38, and Mario Lopez, 36, guilty in the 2020 attack.

Diaz and Sommer were also convicted of assault by a life prisoner, and jurors found that all three men inflicted great bodily injury on the victim.

According to the Kern County District Attorney’s Office, the attack occurred April 23, 2020, while the men were on the exercise yard at the Delano prison. Prosecutors said the three inmates used weapons they had made to stab another inmate multiple times in the face and upper torso.

The victim suffered severe injuries, including a lacerated liver, a lacerated bowel, a life-threatening head wound, and multiple puncture wounds. He also required a chest tube to breathe.

As correctional officers responded, Lopez fled, while Diaz and Sommer continued the assault after knocking the victim to the ground, authorities said.

All three defendants were already serving sentences for crimes committed outside Kern County. Sommer is serving 140 years to life from Los Angeles County for five counts of attempted murder. Diaz is serving 15 years to life after a San Diego County conviction for torture and false imprisonment. Lopez is serving 25 years for carjacking and assault with a deadly weapon in Los Angeles County.

Sentencing is scheduled for May 28, 2026. Diaz and Sommer each face an additional 27 years to life, while Lopez faces an additional 25 years to life.

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