Joshua Kelley-Eklund, Victor Lemus and William Osborn were killed when a grenade they were transporting exploded.
Last week, Lemus' widow filed a lawsuit against Los Angeles County, the Los Angeles County Sheriff's Department and Sheriff Robert Luna, among others.
According to the lawsuit, Lemus' death was preventable.
The Los Angeles County Sheriff's Department has previously said it is updating its training manual and guidelines.