GRAND MARAIS (AP) - A former federal prosecutor will investigate whether criminal charges are warranted against Cook County Attorney Tim Scannell for his relationship with a teenage girl.

Former U.S. Attorney Thomas Heffelfinger has been appointed special prosecutor. He twice led the U.S. Attorney's Office in Minnesota and currently works in private practice.

The parents of the 17-year-old girl filed a petition seeking a restraining order against the 46-year-old Scannell. They say Scannell had been a family friend.

The girl's mother says Scannell told her last year he loved her daughter and was having a physical relationship that involved "kissing and touching, but nothing illegal." The age of consent in Minnesota is 16.

Neither Scannell, nor his attorney, Joseph Tamburino, immediately returned messages.