My parents are in chicago, visiting from india and at my brother's place (in the suburbs). This evening, when they went for walk (in the small nature trail), they were attacked by a dog which seemed to have come from one of the houses and were pushed down to the ground, which caused a fracture to my father's forearm and abrasions to my mother...they tried to get the dog away from them but couldnt...it seems there was an american guy standing a few feet away but did NOTHING when the dog attacked, but instead was laughing at this...he later called the dog and it came towards him but returned to my parents and began attacking and terrorising them again..!!!!

My father has been rushed to the ER and has been admitted for surgery tonight to fix the bones...!!!!! I am VERY ENRAGED at this and am looking at how to pursue this matter legally...My sis-in-law called the police and they are asking for the house number where my parents believe the dog came from, but my parents are not sure....

What is the best course of action apart from suing the owner of the dog for endangering the life of my parents?

Is there a way by which he could be forced to get rid of the dog and be arrested for negligience in keeping the dog on leash? PLEASE ADVISE.