On Friday Greenfield Police observed 21 year old Oscar Martinez De Jesus and 2 female juveniles inside a vehicle at 7th St and Palm in the city limits of Greenfield. During investigation it was learned the females were juveniles from out of the area. Detectives from the Major Crimes Unit responded and continued the investigation and it was determined the victim was sexually assaulted by the suspect. Martinez De Jesus was booked into Monterey County Jail on sexual assault charges.