Crazy Town frontman Shifty Shellshock's sudden death is under investigation ... and law enforcement sources tell us cops are looking into the possibility of a fatal drug overdose.
We're told police and fire responded to Shifty's L.A. area home Monday afternoon, after someone stopped by the house and found his body on the floor.
Our sources say drug paraphernalia and a lighter were found near the body ... which is why police are treating his death as a possible OD.
We're told Shifty -- whose real name was Seth Binzer -- is believed to have been dead for more than 24 hours before his body was found.
As we reported ... the Los Angeles County Medical Examiner announced Seth's passing, and an investigation is underway to determine the cause of death.
Our sources say the case will now be handled by the coroner, who will determine the cause and manner of death.
An autopsy has been completed, but the cause of death is listed as "deferred" ... indicating nothing can be confirmed until results from the toxicology report come back.
FWIW, Seth recently announced he was sober and on the journey to bettering himself. He was only 49.