Disney star Cameron Boyce died in his sleep last month due to epilepsy, according to a Tuesday news release from the Los Angeles County Department of Medical Examiner-Coroner.

"The cause of death was determined to be sudden unexpected death in epilepsy," department spokeswoman Sarah Ardalani said Tuesday. "The manner of death was certified as natural."

TMZ reported that Boyce did not have any drugs or alcohol in his system when he died at age 20, except for an epilepsy medication called Keppra. An initial autopsy was deferred by the coroner's office "pending additional testing," but early information suggested "the death occurred under natural circumstances."

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A day after the cause of death was deferred, Boyce's family said he died due to a seizure that resulted from epilepsy.

"Cameron's tragic passing was due to a seizure as a result of an ongoing medical condition, and that condition was epilepsy," a family spokesperson told E! News July 9.

Since his death, the actor's family has launched The Cameron Boyce Foundation, which "provides young people artistic and creative outlets as alternatives to violence and negativity and uses resources and philanthropy for positive change in the world," according to the organization's website.