soulmate- Captive

 In the serrated marks of the cut off on the remains of the finger attached to the bone, You see this brown orange colored like dirt formed around the edges of the layer of skin, take a scraping; it has metal flake of rust within the layers of cut, "Robert responded."

Officer Cathcart and officer Noble, took a sample of the skin, and inserted it into another plastic bag of evidence into their police satchel. 

I bet this matches the serrated knife that we find out behind Claire's cottage, along the lake, the Sergeant quoted.

Therefore, Sergeant Fitzgerald and Lieutenant Gardner, we're headed back to the police station, while officer Noble dispatched for a corner to pick up the corpse,of Ms.Campton.