NEW DETAILS on the murder and attempted beheading of a man at a Round Rock park. Andrew James Wimsatt sat down on a bench that Monday morning in a plaid blue button-up and shorts. Three minutes later he was dead. A neighbor's camera had already caught Benedict Ogbodiegwu Jr. leaving his house that morning, walking toward the park with something in his left pocket that detectives say looked like a large knife sticking out. He stopped for a drink at the water fountain by the basketball court. Then he found Wimsatt. He came from behind, wrapped his left arm around the man, and started driving the knife into his neck. Wimsatt tried to push him off. He couldn't. He was stabbed several more times before he hit the ground. Then Ogbodiegwu walked around to his left side, knelt down, put his knee on the dying man's chest, and kept going -- sawing the blade back and forth while it was inside his neck. He wiped the blade on his shirt and jogged off toward the pool. Four minutes after he left the park, that same neighbor's camera caught him walking back home, two houses away. That afternoon he turned up at a McDonald's in a different outfit and left as a passenger in a red SUV. The plate traced back to his father's house, nine-tenths of a mile from the bench. When detectives showed him a still from the crime scene video, he admitted it was him. Then said he was never at the park. Then said he has a twin. Asked for his twin's name, he had nothing. Deputies found a trash bag by the garage. Inside: the Honda shirt he was wearing at the murder scene, grey sweatpants with red stains, size 12 Jordans, and a 5.5-inch knife with a wooden handle. The red substance on the blade tested presumptive positive for human blood. The two men had never met. He apparently decided to just stab a stranger. In January, Ogbodiegwu was arrested for theft, which was dismissed. In May, arrested for giving police a fake name - also dismissed. Years earlier, he was arrested for theft. The victim, Andrew Wimsatt, was 62 years old, and an accomplished civil engineer in Texas. He was also an avid nature and wildlife photography enthusiast. Fox News host @greggutfeld called him “supremely gentle. Willing to do just about anything for another person.” Before his murder, Andrew had just returned from visiting his mother a nearby nursing home.