Freestyle motocrosser Mike Cinqmars' death remains a mystery today as coroner's officials have now ordered toxicology tests to determine what killed the 31-year-old after the results of an autopsy performed earlier this week came up inconclusive.Cinqmars was found in an unconscious state at his home by his sister Cassey Fisher on the morning of Friday, December 11 and he was soon rushed to the St. Mary Medical Center in Apple Valley, California, where he was pronounced dead at 2:08 a.m.Cinqmars won a silver medal in the 1999 X Games after finishing second to Travis Pastrana in what was the first freestyle motocross event at the ESPN event. Cingmars gained more fame when he jumped his motorcycle over his two-story Apple Valley home for the MTV cameras.The Californian's career ended in 2001 when he crashed and suffered a broken back.According to reports in the Victorville Daily Press, Fisher said her brother became depressed after the accident."There was nothing he could do in the industry," she said. "He couldn't ride again and he was struggling and he was down and out. He struggled with the fact that he was this rising star and suddenly he couldn't ride anymore."According to the report in the Daily Press, Cinqmars' family had taken him to the hospital after he had lost consciousness the day before he died. Doctors ran tests then released him, telling the family that they suspected some of the painkillers he had taken were incompatible, Fisher told the newspaper."We were the best of friends growing up," Fisher told the paper. "He taught my sons how to ride a motorcycle and was like their second father. We were very close. Our family was very close."A memorial service for Cinqmars is scheduled for Sunset Hills Memorial Park in Apple Valley, California, on Saturday at 11 a.m.