A toxicology report revealed no illegal drugs in Amy Winehouse's system, dampening suspicions that the British songstress died of a drug overdose. The tests found alcohol in her system, but it is not known how much, or whether drinking could have contributed to her death.

Toxicology results returned to the Winehouse family by authorities have confirmed that there were no illegal substances in Amy's system at the time of her death, a Winehouse family rep said in a press statement. Results indicate that alcohol was present but it cannot be determined as yet if it played a role in her death.

The family would like to thank the police and coroner for their continuing thorough investigations and for keeping them informed throughout the process. They await the outcome of the inquest in October, the statement concluded.

The Back to Black singer, 27, was found dead in her North London home on Saturday, July 23. An autopsy performed a few days later was inconclusive.

Amy's father, Mitch Winehouse, has insisted that drugs could not have played a role in his daughter's death, assuring friends and fans that she had long stopped abusing drugs and was working on cutting out drinking altogether.

Bruce A. Goldberger, a toxicology professor at the University of Florida, told ABCNews that it is possible that some drug combinations or certain designer drugs could have gone undetected, or were metabolized before the toxiocolgy test.

He also said that even if Winehouse had not consumed drugs immediately before her death, her history of drug abuse could have contributed to her early demise.

The misuse/abuse of illicit drugs as well as prescription drugs can lead to cardiovascular disease and other changes in the body that can lead to death, Goldberger told ABCNews.com. Alcohol abuse can cause similar changes.

I think the picture that we get by studying Amy Winehouse and her behavior is so different than some of the other stars that we've lost, including Heath Ledger, Goldberger continued. This lifestyle that she lived could have resulted in her death, even though drugs were not found at the time of autopsy.

But Mitch Winehouse claimed his daugher had cleaned up her act years before she died.

Three years ago, Amy conquered her drug dependency, Mitch Winehouse said in the July eulogy for his daugher, which was excerpted in the Daily Mail. The doctors said it was impossible but she really did it.  She was trying hard to deal with her drinking and had just completed 3 weeks of abstinence.

She said, 'Dad I've had enough, I can't stand the look on your and the family's faces anymore.'

Amy had seen a doctor the Friday evening before she died, and received a clean bill of health.

The doctor was happy with her condition, a source told The Sun. When he left on Friday night he had no concerns. Less than 24 hours later she was found dead.

Winehouse had spoken to her security guard, Andrew Morris, at about 10 a.m. on the day she died, and told him she wanted to go to sleep. That is believed to be her last conversation.

When Morris went to wake her several hours later he found her dead.

Police sources told the Sun there were no signs of drugs at the house.

A London drug dealer came forward earlier this month to claim that he sold Winehouse £1,200 (about US$2,000) worth of crack cocaine and heroin hours before she died.

Tony Azzopardi, 53, was questioned by London police on Aug. 1 in an attempt to piece together Winehouse's final hours.

I want Amy's family to know the truth about what happened, Azzopardi told the Mirror.

Amy Winehouse's official cause of death will not be known or released until October.