Question about the cop *spoiler*

So was the cop in on the cover up? There's a flashback where the cop is seen with the parents after they bury Carrie Anne and he also tells Elisa's mom that Ryan has never been in trouble and when he went to visit him at the aunt's house, Ryan was the one caring for the aunt instead of the other way around.

Then we find out he was never sent to live with anyone so does that mean the cop knew and was lying to Elisa's mom? I'm confused because the cop was helpful in the end.