(Salem, OR) -- Oregon State Police are asking for help identifying a car that hit and killed a woman on I-5 south of the Highway 22 interchange. Police say 35-year-old Cassandra Sullivan of Salem was found dead on the shoulder of the southbound lanes by a crew picking up litter. Investigators believe she was killed sometime Monday night or Tuesday morning. The vehicle that hit her could have been a Subaru Impreza, Cross Trek, or a Forrester that was crystal white pearl in color. It should have damage to the right front of the vehicle. Witnesses or anyone with information about the incident should contact Oregon State Police.