Toxicology results have shown there were no drugs or alcohol in Marie Osmond's son's system when he fell to his death from a balcony two months ago.
Instead, coroner's officials ruled that Michael Bryan's fall from the eighth-floor in Los Angeles was intentional.
The 18-year-old had left a suicide note before the incident, however, experts were reported as being keen to delay a decision on the case until drug detection tests came back.
Following the death, Osmond said in a statement that she and her family are in "deep shock by the tragic loss" and she asked people to respect their privacy.
Bryan, who suffered from depression, was one of five adopted children Osmond cared for with her ex-husband.
Last month, toxicology tests on a Wisconsin-based official arrested for driving under the influence found a number of drugs in his system.
State representative Jeff Wood's samples contained two types of sedative, two anti-anxiety medications and a large amount of cough syrup.
Product directory
