RSBM
It was still dark out. Darkness helps a lot. But even with daylight, would anyone convincingly recognize that tiny, distant figure and report it to police?
I remember the case of another front yard murder, Dan Markel: there was no camera, but police did track the vehicle to an image captured by a bus that it passed shortly after the murder. But this was in broad daylight, so LE could see the vehicle had a toll transponder. They checked the toll station(s), got a dozen potential vehicles to investigate, and tracked the correct one to a car rental agency and the person who rented it. That led to unravelling the case.
Police need a key piece of evidence that gives them that direct tie from the crime to the perp. They have no crystal ball to gaze at. It's often just sheer luck, that they find it.
It seems as soon as police/public implement one system of detection, determined criminals set to work figuring out how to thwart it. For example, murdering the victim outdoors, so no chance of leaving DNA, fingerprints, etc.
JMO