Complex sentence: It was assumed that Jennings had a problem with drugs, which may have contributed to her death, however the coroner's report showed that there was no presence of drugs or alcohol in Jennings' body at the time of the accident.
Split into simpler sentences: It was assumed that Jennings had a problem with drugs, and that it may have contributed to her death. An autopsy, however, showed that there was no presence of drugs in Jennings' body at the time of the accident.