A lot that doesn't make sense. SPOILERS
So first of all - let's take the part where he's pursued by a man who he then in turn pursues. Never mind that it makes no sense for the killer to be chasing him (or to run from him really) at that point. Instead of following him, why didn't he just go back to the car? He'd seen the guy come out of his van, so he has to come back there to get it. Meanwhile he could run the plates to ID him.
Then there's the Gerri Harden alias. They could simply have found out where the money was going for the artworks that had sold (the gallery rep says they've been selling even though they all seem to be there). Whoever is cashing the cheques is the killer. And if they had prints on file to get a name and last known address, that means that 'Gerri Harden' has been arrested in the past - yet this person doesn't exist. How'd they get a name and address from prints of someone who is imaginary? They should have come up with the killer's name, not his alias.
At every step, the cops avoid the obvious methods of determining the killer's identity, instead preferring to be drawn along. There's no logic in it. Why does the cop refuse to work with other cops? Why doesn't he tell anyone what he's learned or where he's going? It's just too much of a mess in terms of plot to be compensated for in other areas.
"I'll book you. I'll book you on something. I'll find something in the book to book you on."