WESTPORT — Brian Joyce, the former state senator who was found dead in his home in September, died of an overdose of a sleep-aid medication, according to the Massachusetts Chief Medical Examiner's Office.

The Medical Examiner released the findings of Joyce's autopsy Tuesday, saying the 56-year-old Joyce died of acute pentobarbital intoxication. Pentobarbital is a sedative that is commonly used to treat insomnia.

Joyce was found dead in his Westport home by his wife on September 27. The former state senator had been involved in a car crash the night before, according to Westport Police.

The autopsy also revealed slightly elevated levels of citalopram, which is used to treat depression. Evidence of hypertensive and atherosclerotic cardiovascular disease was also present.

Though the cause of death has been determined, the Bristol County District Attorney's Office says it's still unclear if Joyce's death was accidental or a suicide. Foul play is not suspected.

The Bristol County District Attorney's Office is reviewing the Chief Medical Examiner's autopsy report and will determine whether further investigation is warranted.

Joyce had been under federal investigation and pleaded not guilty last year to corruption charges. Prosecutors said Joyce accepted bribes and kickbacks totaling $1 million and laundered the money through his law office.

Court records show that U.S. Attorney Andrew Lelling dismissed the charges against Joyce in October, citing his death.