Disney star Cody Linley’s older brother Chad died in August and RadarOnline.com has exclusively learned it was from the toxic effects of heroin.

According to the Harris County Institute of Forensic Sciences in Texas, Chad’s manner of death was ruled an accident, but the cause was “Toxic effects of heroin.”

As RadarOnline.com was first to report, Chad, 29, was found in his Houston, Texas, apartment in August by his apartment manager.

Hannah Montana star Cody Linley’s older brother, Chad, died on August 6 in his Texas home and RadarOnline.com has exclusively learned the 29-year-old was once a promising actor who was ultimately outshined by his younger brother.

Nearly 16 years ago, Chad lived with his brother Cody and mother Cathy Sullivan in a 475-square-foot apartment in Los Angeles where they’d moved for “pilot season” from Dallas in an effort to launch the then 13-year-old Chad’s career.

“Chad had gotten a few bit roles, but his mom was an acting coach and the family was determined to make him the next Macaulay Culkin,” a source exclusively told RadarOnline.com.

Hannah Montana star Cody Linley’s older brother, Chad, died earlier this month and RadarOnline.com has learned exclusive new details about his mysterious death.

While there is still no official cause of death, the Harris County Medical Examiner in Houston, Texas, tells RadarOnline.com they have conducted an investigation and it’s pending the toxicology reports, which could take weeks.

“A friend of Chad’s called and said he was concerned because he hadn’t heard from him in a while,” a spokesperson for the Houston Police Department said.

Hannah Montana star Cody Linley’s older brother, Chad, has died, aged just 29.

There has been no official word on how, why or where Chad died yet but his friends and family have taken to Twitter to share their grief and support.

Disney star, Demi Lovato tweeted on Wednesday: "RIP Chad Linley...Knew you since I was a kid.. You were family... You will
be missed... Please #prayforcodylinley and his amazing family."