(CNN) -- Toxicology tests have found that "no illegal substances" were in singer Amy Winehouse's system at the time of her death last month, her family said Tuesday.
"Results indicate that alcohol was present but it cannot be determined as yet if it played a role in her death," the family said in a written statement, citing test results provided to them by authorities.
The 27-year-old singer, beloved for her talent but infamous for erratic public behavior, arrests and drug problems, was found dead at her apartment in London on July 23.
Winehouse's soulful, throaty vocals brought the British musician stardom in 2007, but her troubled off-stage life -- chronicled in her top 10 hit "Rehab" -- won her notoriety. Her death came less than two months after her latest release from a rehabilitation program and weeks after she was booed offstage by disappointed fans in Serbia.
"Rehab," in which she sang "They tried to make me go to rehab, I said no, no, no," helped form the public's view of Winehouse. But she told CNN in a 2007 interview, "I don't care enough about what people think of me to conform to anything."
The London-born singer-songwriter became a picture of a tattooed teenage rebel after she was expelled from a prestigious performing arts school. Her first album, "Frank," debuted in 2003, when she was 19.
International success came with her 2007 album "Back to Black." She dominated the 2008 Grammys, winning five awards that night and delivering, via satellite from London, a strong performance of "Rehab."
Winehouse's volatile marriage to Blake Fielder-Civil took a toll on the singer's career. The couple divorced in 2009 after a stormy two years filled by drug addiction and arrests.