Some people believe that a hired hitman killed the Bamber family. I can´t see it happening. First of all Jeremy would have made sure to have an airtight alibi - he didn´t have that.
Secondly, can you imagine standing outside that house, knowing there are three adults in there? There are FIVE people you have to kill - an overwhelming task, right! For 2000 £. I am not buying it.
Same goes for Jeremy doing it. It would have seemed as overwhelming to him to do ALONE.
If you choose to believe that Jeremy is the guilty one, isn´t the most likely scenario that he had an accomplice?