Aug. 23, 2011 -- There were "no illegal substances" found in Amy Winehouse's body at the time of her death, her family claims, according to The Associated Press.
The family revealed the results of a toxicology test in a statement released today.
"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," the statement read. "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.
Winehouse's formal cause of death remains unknown and will be not be released until October.
The 27-year-old singer was found dead at her flat in London's Camden district July 23.
Officials reportedly found no drug paraphernalia or sign of drugs in Winehouse's home.
Bruce A. Goldberger, a toxicology professor at the University of Florida, said the negative toxicology result does not completely rule out the involvement of a drug or a combination of drugs that could have been missed by the testing procedures or were metabolized before the test.
He said some prescription drugs, illicit drugs and "designer" drugs can escape detection.
Nor does this test result rule out the toll years of drug and alcohol abuse could have had on Winehouse's body.
"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 said. "This lifestyle that she lived could have resulted in her death, even though drugs were not found at the time of autopsy."
Soon after her death, her U.K.-based representative Chris Goodman revealed that a bodyguard hired to watch the singer was the first person to discover her death.
"She was in her bedroom after saying she wanted to sleep, and when he went to wake her, he found she wasn't breathing," Goodman told the Sun newspaper. "He called the emergency services straight away. He was very shocked. At this stage no one knows how she died. She died alone in bed."
The Sun also reported that Winehouse had seen a doctor the night before she died as part of a routine series of checkups, given her history of drug and alcohol abuse. The doctor saw nothing wrong.
The Grammy-winning singer was literally rocking out the night before she died, according to People magazine,
"We know that she was well enough to be playing drums well into Friday night," said Julie Dam, People's assistant managing editor. "We spoke to neighbors who said she was usually so quiet. It's worth noting that she was making a lot of noise that night."
But Winehouse's clean bill of health and activity prior to her death might have masked underlying problems from years of substance abuse that eventually killed her.
"She may have had asthma and emphysema because of her smoking," said Dr. Eric Braverman, an addiction specialist and author of the book "The Edge Effect." "From that, you can have a terrible respiratory arrest. You can have a seizure. Your lungs can choke off your trachea. It happens in asthmatics a lot."
Respiratory conditions might not have been picked up by Winehouse's physician.
"If you have a pulmonary disease, you need a lung function test, not a stethoscope," Braverman said. "So a simple physical that tells you you have a clean bill of health doesn't say much."
Winehouse's father told reporters in 2008 that she had been diagnosed with early-stage emphysema. She was also vocal about her struggles with eating disorders, which could have played a part in her death, too.
"You can also suffer cardiac arrhythmia from dieting and not eating properly," Braverman said. "Even panic attacks in her state can constrict the lungs and bring on death."
Kelly Osbourne and Mark Ronson were among the famous friends who attended Winehouse's funeral July 26, during which her family and friends sang her favorite song, Carole King's "So Far Away."
Winehouse's rep Goodman told Britain's Daily Mail that her father gave a touching eulogy at the ceremony.
"Mitch's last words to Amy in his eulogy were 'Goodnight my angel,'" Goodman said. "Sleep tight. Mummy and Daddy love you ever so much."
Reg Traviss, Winehouse's most recent boyfriend, attended the funeral and spoke to the Sun about the singer's death, saying "I have lost my darling who I loved very much." Blake Fielder-Civil, Winehouse's ex-husband, was not in attendance. He's currently serving a 32 month jail sentence.
ABCNews.com's Carrie Gan and Lara Salahi contributed to this report.