Grand jury investigating LASD's handling of deputy-inmate altercation

A criminal grand jury is investigating how the Los Angeles County Sheriff's Department handled an incident where a deputy knelt on a handcuffed inmate's head for three minutes in a San Fernando court lockup.

The incident happened last year but recently leaked surveillance video led to allegations that the LASD tried to cover it up. 

LA County Sheriff Alex Villanueva has repeatedly denied those claims. 

In a statement Monday, Villanueva said his office is fully cooperating with the grand jury.

Several department officials have been subpoenaed and will testify later this week.