In a tweet, Villanueva says he's committed to strengthening community faith in the investigative process.
"Out of an abundance of caution, I reached out to @AGBecerra for monitoring of the Guardado investigation," the sheriff tweeted.
Out of an abundance of caution, I reached out to @AGBecerra for monitoring of the Guardado investigation. I am committed to transparency and strengthening community faith in the investigative process.— Alex Villanueva (@LACoSheriff) June 23, 2020
Meanwhile, lawyers for Guardado's family say the sheriff's department has put a "security hold" on the autopsy results.
Gardena shooting: Local leaders call for independent investigation as authorities examine security cameras at scene of 18-year-old's death
They are demanding answers and accountability.
"(The family of Andres Guardado) demand, and deserve, full transparency from the Los Angeles County Sheriff's Department regarding the facts surrounding the death of this young man," a statement from attorney Adam Shea said.
On Sunday, sheriff's deputies and protesters clashed during a demonstration in Compton over the death of Guardado.
The sheriff's department made seven arrests, including six for unlawful assembly. They used flash-bangs, pepper balls and smoke grenades, saying objects were thrown at deputies.
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A curfew was put in place in Santa Ana Monday evening, prompted by protests related to the fatal shooting. The curfew is in place from 10 p.m. Monday until 5 a.m. Tuesday.
Deputies shot and killed Guardado last Thursday after they say he pulled out a gun and ran from deputies on patrol in the 400 block of Redondo Beach Boulevard.
His family said he was working as a security guard in the area, but authorities say he was too young to be state licensed and did not have a uniform or badge.
Some local political leaders are asking for a state investigation into the shooting.