Paul Gray's doctor has been charged with the involuntary manslaughter of the Slipknot rocker.

The bassist died of an accidental overdose in June 2010 and his physician Dr. Daniel Baldi is to face charges of prescribing high amounts of painkillers to people who later died.

The medic - who is being investigated over the deaths of eight people, including the rocker - is also facing administrative charges from the Iowa Board of Medicine, which could lead to suspension of his medical licence.

However, his lawyer Guy Cook called the charges ''unprecedented''.

He told the Des Moines Register: ''It is unprecedented to turn unfortunate deaths or medical results into a crime against a doctor.''

The charging documents relating to Paul - who struggled with addiction - said the doctor ''did unintentionally cause the death of Paul Gray by the commission of an act likely to cause death or serious injury, to-wit, continually wrote high-dose prescription narcotics to a known drug addict from 12/27/2005 until his death.''

Slipknot percussionist Shawn Crahan and Paul's widow Brenna are listed on the preliminary complaint filed in district court as among nine people interviewed in the investigation.

Slipknot are set to issue a statement later today (06.09.12) about the case.