Why was the young student killed ? - Josh was killed because he had written a exposé on the company of the Children's home and the money they were making, and what they were doing.
It seemed a bit daft. His father was the accountant for the company, and involved with the company.
Who killed the killer with heroin and fentanyl? Josh's mum was a GP and gave the drugs to the boy from the care home, by being persuaded by his Dad. He thought Chloe would be there.
Why ? Because he committed the first murder, and killed him because of it.
Was Chloe being followed because she knew who killed both ? She saw the murder of Josh happen, because she was following him as she had a crush on him.
The father, in the final confrontation didn’t appear to be grieving much.
Chasing after a young girl in the countryside when his son was lying in the mortuary.....
I agree he only broke down when ever thing was over.