Complex sentence: Investigators found the 1986 silver Calais that Renkoski had been driving, but it was not processed as a crime scene because at the time it was considered by the responding officer to be an abandoned vehicle.
Split into simpler sentences: Investigators found the 1986 silver Calais that Renkoski had been driving. It was not processed as a crime scene because at the time it was considered by the responding officer to be an abandoned vehicle.