The length of time is frustrating but the SIU investigations are thorough and detailed. Some of the timing such as ballistic tests and laboratory analysis would be beyond their control. Here is a link to a report released last week from an incident in September that gives an idea on the detail that goes into their investigations. I would expect the Kotanko matter to be more complex than this one.
https://siu.on.ca/en/directors_repor....php?drid=1772