Okay, Who Left That Grenade at the Botanic Gardens?

Authorities Sunday afternoon responded to a "found grenade" call from the South Coast Botanic Gardens in Palos Verdes Estates.
The grenade was found along the Banyan Grove Trail, adjacent to Crenshaw Boulevard, says the Los Angeles County Sheriff's Department. Deputies from Lomita Station and Parks Bureau enlisted the aid of the Arson Explosives Detail once the location was secure.
But, phew: The device was determined to be an Inert Grenade Body (containing no explosives), says the LASD, and they took the device to destroy it.
So who left the grenade at the park? Well, one theory is that a recent movie production may have left this one prop behind, says the LASD, but the incident remains under investigation.