Officer Marvin Siebert was riding his police motorcycle westbound on San Leandro Street on September 19, 1951. As he entered the intersection of 73rd Avenue, a vehicle pulled in front of his motorcycle, causing a head-on collision. Thrown over the hood of the vehicle, Siebert landed on the pavement headfirst.
Siebert remained in a semi-conscious state at the scene and during the trip to the hospital, where he died of his injuries shortly after arrival.
Siebert joined the Oakland Police Department in October 1947. He was unmarried and was survived by his mother and a sister. The driver of the vehicle was arrested for manslaughter and violation of the right-of-way.