The medical examiner reported that the body found was about 71 pounds, but the girls last known weight was listed at 120 pounds. To lose almost half her body weight like that means she had to be on that car for months. The evidence overwhelmingly points to him, but it’s may be hard to tie any physical evidence to him since the body done deteriorated so bad. Also, they will have to figure out when she was killed and that can be hard with the body sitting for that long.
So they are gonna have to get warrants for and go through all the other evidence like digital evidence, and talk to people of interest to build clear motive and timeframe. Then they will arrest him. They likey just don’t have enough for a strong case right now, but will get in the next few weeks to few months