A soccer coach who a California family says was the last person who had contact with their dead son is a person of interest in the boy’s disappearance and was arrested on an unrelated sexual assault case … has confirmed.

Missing 13-year-old boy Oscar Omar Hernandez was found dead in a ditch earlier this week in Oxnard and his family says he was last seen with his soccer coach, 43-year-old Mario Edgardo Garcia Aquino.

Our law enforcement sources tell us … Aquino was questioned by cops and was arrested … but not for Oscar’s death or disappearance.

Instead, we’re told Aquino was busted by LAPD detectives on a warrant from an unrelated sexual assault case that was previously investigated by the Los Angeles County Sheriff’s Department.

Aquino is facing one count of assault with intent to commit another felony, which prosecutors allege was the attempted rape, sodomy or oral copulation of a man for the 2024 sexual assault case … according to NBC4, which was first to report Aquino’s arrest.

The alleged sexual assault reportedly went down in February 2024 … with LASD’s Special Victims Bureau investigating.

Oscar’s body was found in Oxnard but he’s from the San Fernando Valley in L.A.