Jade Harris was last seen alive on October 25th. Surveillance footage shows her ex-boyfriend driving her car on the 26th. Her ex, despite being barely 21, has an ample arrest record. A sensible person would figure out that, if he can't even handle drugs without being arrested, he's not going to be able to get away with murder.
Apparently he has a swastika tattoo, which demonstrates exactly how much sense he possesses.
Jade's killer is now serving 30 to life.