Kris Kross rapper Chris Kelly's death has been officially ruled a drug overdose.

The 34-year-old star - who formed one half of the 90s teen hip-hop duo - was found unconscious at his Atlanta home on May 1, before being pronounced dead.

According to TMZ, an investigator from the Fulton County Medical Examiner's office said he died with a fatal mixture of drugs in his system.

While the drugs were not specified, Chris' mother admitted her son had been doing cocaine and heroin the night before he died.

Kelly, known as 'Mac Daddy', and his Kris Kross bandmate Chris Smith, known as 'Daddy Mac', were discovered at the tender age of 13 in an Atlanta mall by music mogul Jermaine Dupri.

The energetic duo - whose trademark was wearing their baggy clothes backwards - burst onto the scene in 1992 with one of the biggest songs of the year, 'Jump', from their multi-platinum debut album 'Totally Krossed Out'.

The pair enjoyed a meteoric rise to fame, joining Michael Jackson on his Dangerous World tour and even appearing in his 'Jam' music video.

Kriss Kross went on to record two more albums, and had success with singles 'Warm It Up' and 'Tonite's tha Night'.

Kelly - who was studying to become a musical engineer - and Smith performed together for the first time in years in February at the 20th anniversary bash for Jermaine's So So Def record label.