French investigators studying dermatologist's murder

French investigators have arrived in the United States, looking to study evidence in the case of a dual citizen accused of killing a Chicago dermatologist in 2006.

An arrest warrant was issued in Chicago for Hans Peterson Dr. David Cornbleet's death. But Peterson turned himself in to French authorities.

A French judge has ruled Peterson won't be extradited.

The French investigators are to decide if Peterson will be prosecuted for murder in the French judicial system.

Cook County state's attorney's office spokesman John Gorman says prosecutors hope the French officials change their position on extradition.

Cornbleet's son, Jon, of Naperville, has alleged Peterson killed the physician after being prescribed an acne medicine that he believed made him impotent. Police and prosecutors have not publicly commented on a possible motive.