It is perhaps worth pointing out (again) that the police role is solely to gather evidence. It is for the CPS to assess the evidence obtained and make a decision as to whether it is admissable, obtained fairly (from a legal standpoint), and whether the evidence is sufficient to bring a criminal case before the courts with a reasonable chance of obtaining a successful prosecution.
There is a completely separate procedure for civil action(s) mounted to obtain damages.
A Coroners Inquest into the deaths will also come up with its' own set of findings that may impact on criminal and civil procedings.