CHICAGO, Illinois (CNN) -- A man suspected of murdering a doctor in Chicago, Illinois, is trying to skirt the U.S. justice system by fleeing to the French island territory of St. Martin, according to prosecutors. 

Dr. David Cornbleet, a dermatologist, was murdered in his Chicago office in October, 2006. 

"He's doing everything possible to protect himself," said Bernie Murray, chief of criminal prosecution for the Cook County State's Attorney's Office in Illinois. "At the end of the day, he's making a mockery of both French law and United States law." 

After fleeing to St. Martin, Hans Peterson, 29, turned himself in to French authorities and allegedly confessed to murdering Dr. David Cornbleet in October, 2006. Jon Cornbleet, Dr. Cornbleet's son, said he has seen a four-page confession in which Peterson admits to attacking and killing David Cornbleet in his Chicago office. 

Despite the alleged confession, Peterson is beyond the reach of U.S. law enforcement. As a French national on French soil, he cannot be sent to the United States for trial, according to a 2002 extradition treaty between the two countries. The United States, by contrast, is allowed to extradite U.S. citizens to France, under the treaty. 

U.S. Sens. Barack Obama and Dick Durbin, both of Illinois, sent letters to Secretary of State Condoleezza Rice asking for help extraditing Peterson. In response to the senators, the State Department wrote it "will continue to make every effort with the government of France to see that justice is served in this case." 

Sens. Durbin and Obama also wrote the French government requesting extradition. 
Is there anything that can be done?
the State Department wrote it "will continue to make every effort