Son Caught "Shoplifting" Shoelaces at Kohl's - Now What?

My son, 17, went to Kohl's yesterday to purchase tennis shoes. He saw a pair that had 2 pairs of shoestrings-black & blue-and thought the blue strings were cool. He took the blue strings, stuffed them in his pocket. He purchased a different pair of shoes and left. Security guard stopped him outside, accused him of stealing the shoelaces. My son was pulling out car keys-security grabbed his hand & keys, said he might be pulling a weapon. He was taken to a back room, my husband went there to take care of the situation. They were forced to sign papers, else they were going to take my son to the police station. Both my husband and son were treated very badly. Kohl's says they are going to prosecute for full cost of shoes-$64 (though they're clearance!) Is this right? How should we proceed?