Junkins ... and the spirit world!

Does Junkins ever know that Christine is a haunted, sentient car?

From his perspective, he was aware of the vandalism case when Christine got trashed, and then took up the far more serious investigation of the murder of Moochie. Later, all the other guys are killed too so although Arnie seems to have good alibis for their deaths, he is intrinsically linked to their deaths.
Darnell found dead in a perfect Christine, while Arnie is away.
Someone is killing, and if not Arnie for revenge then who?
Though there is a extra scene where Junkins mentions the red paint on Moochies pelvis, why does he not consider how Moochie was "cut in half" in that dock too narrow for the red car?

And then at the end, he's all on board with the crushing of Christine. But really? As far as he's concerned, Leigh left Arnie and is now Dennis's girl and all 3 met up in Darnell's garage whereupon Dennis crushed the car and presumably killed Arnie.

"No detective, the car killed Arnie, it's haunted and can rebuild itself you see. I had to destroy it"
"Ohhhh, well that explains it. You're free to go Dennis. Case Closed"
Junkins never saw Christine do anything to convince him of the truth.