WTF?

This story is horrific. I am eager to find out more about what caused this senseless tragedy. From today's Toledo Blade:

Roland Gladieux was awakened yesterday morning by two men arguing outside his house in South Toledo. Still groggy, Mr. Gladieux peered out his bedroom window about 5:40 a.m. and saw one man hovering over a man on a bicycle, threatening to shoot him. Seconds later, there was a gunshot and the victim fell backward. “I saw him pull the trigger,” Mr. Gladieux said. “I seen the gun flash.”The victim, David Babcock, 46, of 908 Kingston Ave., who was riding his bike to work to save money on gas, was shot once in the corner of his mouth in the 800 block of Western Avenue, near Langdon Street. It was the first time he had set out on what was to be an eight-mile ride to work.
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Thirteen years ago, Mr. Babcock was diagnosed with a brain tumor and, despite the odds, fully recovered from the surgery to remove it.“Doctors didn’t think he’d walk and talk again, let alone live this long,” his fiancee, Rene Long, said.Toledo police Capt. Ray Carroll said authorities are unsure why the two men were arguing, but according to witnesses, it was a heated exchange. “It was enough to wake people up at that hour,” the captain said.