First time poster, what a great site and what a great thread from all the amazing contributors. Really, first class.
Here’s my two-penneth (all my humble opinion) based on what I’ve read:
In my humble opinion the police aren’t looking for anyone else, I opine they probably know who the 5 people involved are. It’s possible the 5th person may have been publicly defending the other 4 possibly because the 5th person may have killed CL and the 4 could potentially be accomplices who helped clean up the scene - being well versed in doing that. The 5th person could have been young, naïve and jealous. The 5th person may have been good friends with CL. The 5th person may have been or may continue to be in a relationship with one of the other 4?
CL being single could have had a fling with at least one of the other 4 and that one could have been or continue to be in a relationship with the 5th person. The 5th person could have found out about this, possibly when CL was drunk either told directly by CL or indirectly. This could be why CL was acting unusually and avoiding the NH and the 5th person.
The 5th person could have had means of accessing CL’s house - possibly by key if they had one from the past or possibly from one of the 4 who had a known obvious interest in locks. Maybe the 5th person had first hand experience of CL’s morning routine to make it look like CL had left in the morning. It’s possible the 5th person strangled CL with the hair straighteners cable in a fit of jealousy - over the fling. The other 4 may have helped the 5th person dispose of the body.
Perhaps the man and woman arguing are the 5th person and one of the other 4, possibly her lover, and they’re trying to come to terms with what’s happened and what to do next.
All of the above is all my humble opinion only.
Thank you to all the hard work which has gone before me.