Pneumonia — not a drug overdose — killed Anna Nicole Smith, the National Enquirer has learned exclusively.

In the new issue just hitting newsstands, The ENQUIRER reports that preliminary findings reveal that tests performed during the autopsy show Anna Nicole had a severe case of pneumonia. Prescription drugs that she had taken made the condition worse and did play a role in her death. The full toxicology report has not yet been completed.

Sources very close to the death investigation told The ENQUIRER that the prescription drugs masked the seriousness of her pneumonia. Anna Nicole had previously been hospitalized for pneumonia in the Bahamas after her son died.

This time, the painkillers Anna Nicole was taking masked her symptoms and quickened the deadly effects of the pneumonia.