France will not extradite an American suspected of killing a dermatologist in Chicago last year, saying it cannot do so because he also is a French citizen.

Hans Peterson, who turned himself in to French authorities Aug. 6 on the Caribbean island of St. Martin, will be tried in a French court in the slaying of Dr. David Cornbleet, Emmanuel Lenain, a spokesman for the French Embassy in Washington, D.C., said Friday.

An arrest warrant was issued for Peterson in Chicago in the death of Cornbleet, who was fatally stabbed in his downtown office in October.

The French government told U.S. authorities it is refusing their extradition request because of proof Peterson is a French citizen, according to Bernard Murray, a spokesman for the Cook County state's attorney office.

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Peterson is a U.S. citizen, but he also is a French citizen because his mother is French, Lenain said. Peterson, 29, is being held in French-controlled Guadeloupe in the Caribbean, but he has yet to be charged, Lenain said.

Murray said France typically doesn't extradite in cases where the suspect may face the death penalty. Peterson has not yet been charged in the case, so no potential penalty has been determined. The death penalty remains on the books in Illinois, though a state moratorium on carrying out executions has been in place since 2000.

Lenain, however, said Peterson's citizenship means the French will not extradite him no matter what penalty he could face in the U.S.

"It's not a decision by our government, it's just a legal provision in our law," he said. "We can't do it. We've never done it."

Bob Milan, a Cook County prosecutor, said last week it is important that the suspect be brought back to Chicago rather than be tried in a French court.

"Their maximum for murder is 20 years and he would serve 16," said Milan. "That's unacceptable."

Illinois' two U.S. senators, Dick Durbin and presidental candidate Barack Obama, have written to the French Embassy saying that Peterson should face prosecution in the U.S. in Cornbleet's death.

Cornbleet's son, Jon, 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.

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