please help and thank you

3) Mark had been dating Linda for six months. Linda had a six-year-old daughter named Debbie. Mark usually spent Friday and Saturday night at Linda's house. On Saturdays he did jobs around Linda's house. One Saturday Debbie was playing in the front yard while Mark was up on a ladder working on the rain gutters. Mark observes that a group of boys, who appeared to be a few years older than Debbie, were congregating in the front yard. Initially they were just talking and laughing, but after a while Debbie started saying, "No. Go away." Then the boys grabbed Debbie and she started screaming. Then they dragged her down the street. All this time Mark was observing from his position on the ladder. He didn't shout at the boys, he didn't call anyone using his cell phone. About fifteen minutes later there was a sound of sirens. Finally Mark got down from the ladder and walked over to see what was happening, Debbie had tried to break free of the boys and ran out into the street, where she was fatally struck by a motorist. During the investigation that followed, Mark stated that he thought Linda was inside. Linda told police that she had told Mark she was going to the grocery store and to keep an eye on Debbie. Mark denies that she said that. Please identify all of the legal issues presented and discuss fully