If Jeremy was guilty why would he:
1) Blame the police for killing his family
2) Say to the police he wasn't getting along with his sister
3) Not get an alibi
4) Finish with Julie Mugford a few weeks after he had told her he was responsible for the murders
5) Say he was responsible for leaving the gun on the table
6) Go away on holiday leaving a silencer in the cupboard which was used in the murders
more to be added