Filmmaker Tony Scott had an anti-depressant and sleep aid in his bloodstream when he leapt to his death from a suspension bridge in August, the Los Angeles County Coroner's office said on Monday (local time).

Preliminary autopsy results confirmed that Scott's death, which baffled investigators and much of Hollywood, was a suicide, caused by blunt force trauma and drowning.

The 68-year-old British-born director of such blockbusters as Top Gun and Beverly Hills Cop II had therapeutic levels of the anti-depressant Mirtazapine and the prescription sleep-aid Lunesta in his system, coroner's investigators found.

But the findings shed no light on a motive for Scott to commit suicide. A coroner's spokesman said a final report was still two weeks away.

Family members have dismissed early reports that Scott was suffering from inoperable brain cancer and Craig Harvey, operations chief for the coroner, has previously said that there were no obvious signs of a tumour. The preliminary autopsy report made no mention of any evidence of serious illness.

Investigators have offered no theories as to why Scott took his life, and a note he left behind did not explain the suicide.

The last person to see Scott was an onlooker parking his car on the Vincent Thomas Bridge over Los Angeles Harbour, who saw the director leap into the water just after noon on August 19. His body was recovered by law enforcement several hours later.

The bridge, the surface of which clears the harbour's navigation channel by a height of about 56 metres, connects the port district of San Pedro at the southern tip of Los Angeles to Terminal Island in the Harbour.

Scott, born in northern England and frequently seen behind the camera in his signature faded red baseball cap, is credited with directing more than two dozen movies and television shows and producing nearly 50 titles.

He built a reputation for muscular but stylish high-octane thrillers that showcased some of Hollywood's biggest stars in a body of work that dated to the 1980s and established him as one of the most successful action directors in the business.

At the time of his death, Scott was reported to be involved in developing several film projects including a sequel to his biggest hit, the 1986 fighter-jet adventure Top Gun, which starred Tom Cruise.

The brother of Oscar-winning director Ridley Scott, he is survived by his third wife, Donna, with whom he had two children. 

- AP