I will answer all your points.
First, it was Officer Matthews job and duty to provide backup to the officer that was pursuing Pierce.
Second, if Pierce had just stopped like a normal person would have done; IE non criminal, Officer Matthews would not have been driving as fast to provide backup. All actions are related to Pierces' actions.
Third how swell would that work to jot down the tag and let the vehicle go to find out it is a stolen tag that hadn't been reported as stolen yet? And then if it wasn't a stolen tag, how do you prove who was driving the vehicle? Lawyers love the term "reasonable doubt". In court they wouldn't have to prove Pierce wasn't driving, they would only have to put out there that since the WPD didn't actually stop the vehicle, they don't know who was driving. It might have been one of his many cousins he frequently loans his vehicle to. Or could say the keys are often left in the vehicle, maybe somebody took it for a joy ride. But when he is caught in the drivers seat, on video, it is hard to then say it isn't you that decided to run from the police. You say the ones who were chasing him were enough, there was only one officer directly behind Pierce and that is why Officer Matthews was responding at that rate of speed.
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