Amy Winehouse

No illegal drugs were in Amy Winehouse's system at the time of her death, yet it remains unclear how she died, her family said.

Amy Winehouse autopsy inconclusive; burial set

"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. Results indicate that alcohol was present but it cannot be determined as yet if it played a role in her death," the Winehouse family said in a statement to The Associated Press.

Winehouse, who had long battled alcohol and drug abuse, was found dead at age 27 on July 23. An initial autopsy failed to determine the cause of death.

Her family has maintained that Winehouse had been clean and believes that giving up alcohol cold turkey killed her.

Amy Winehouse's family says alcohol withdrawal killed her

The Winehouses are awaiting the outcome of an inquest into the singer's death that is scheduled to begin in October, the statement added. "The family would like to thank the police and coroner for their continuing thorough investigations and for keeping them informed throughout the process."