The ipcc appear to have been happy to sweep this under the carpet until that video surfaced.
I'm not sure the sequence of events can be characterised as them "sweeping it under the carpet". In any sudden (initially unexplained) death, there is a period in which there is a "shall we, shan't we" mount a full homicide investigation. Not least due to wasting scarce resources, full investigations are not launched until non-crime explanations are eliminated. This frequently (as in this case) means waiting for the cause of death from a post-mortem. Here the result indicated that the death was apparently not homicide (although it is not unusual for heart attacks to follow from confrontation / minor assault, they are almost always at the time of the confrontation / assault and this was known not to be the case here on the basis of independent witnesses to the actual collapse).
In the meantime, however, whilst awaiting the PM result or whatever, all necessary steps should be taken to secure evidence (from scene examination, witness enquiries or whatever) - if it tunrs out it is homicide you can't come back and do it later (at least not as well) but if it isn't the only thing that has been wasted is the time taken in the enquiries.
The IPCC were overseeing the initial investigation and there is nothing to say that they would not have continued to oversee it even if the video had not surfaced - they
may have decided to entirely exit from the case but that would not normally be the case - even if they did not take any active role they would normally still receive the final report.
That said, I think if the decisions had been mine I would have erred on the side of caution significantly more. The initial referral to the IPCC was right. If I was the IPCC I would have
immediately taken over the investigation, at least as a managed investigation, and would have taken immediate steps to investigate the time line back from the point of collapse to ensure there was no physical confrontation which
may have been linked to the collapse. If I had knowledge of the marks which were apparently on the body (and if they had not been reported by the pathologist there would be serious questions to ask of them - unfortunately for some reason the Coroner (and it is their decision, not the police's) appears to have appointed an improperly authorised pathologist)) then I would
definitely do so, even if I hadn't originally. My time line would go back probably to him leaving his paper kiosk and I would want to fill in everything that happened to him since (as was in fact done to some extent by the media in the following days).
There are definitely questions to be asked of the IPCC as to why they decided not to intervene more robustly initially and (if they did not) why the police and IPCC did not proactively try to pursue the time line back from the point of collapse.
