What point are you trying to make?
Did the presumably new information change your mind? Or do you still think it was a standard part of a liberal democracy?
Here's the then Canadian PM's apology after 25 years. https://nationalpost.com/news/canada/stephen-harpers-apology...
Fair trials are indeed a cornerstone of liberal democracy, with fairness being an attribute given to those accused of a crime, not necessarily the unfortunate victims. The accused tends to get the benefit of the doubt because of the cost of the loss of freedoms that hinge on a guilty verdict. CSIS fucked up. The RCMP fucked up. But there is a standard to which prosecutions are held and the government didn't meet it.
And none of this excuses _gunning down a person sitting in their car_ which, in case you forgot, was the original topic of this discussion. It doesn't matter who they associated with, what they were involved with, or what they did.
True, the Indian government fucked up.
There is evidence that CSIS destroyed evidence that led to the acquital of the defendants. And your response is "CSIS fucked up. The RCMP fucked up." Nothing to see here!
[1] https://espionage.substack.com/p/canadian-intelligences-dirt...
[2] https://espionage.substack.com/p/how-canadian-intelligence-a...
As for liberal democracies: you'll find many examples of the spies (i.e. counter-intelligence) working at cross purposes to the criminal justice system. Think MI5 vs the Met, or the NSA vs local law enforcement. The spooks are often much more interested in protecting sources and methods than they are in criminal prosecutions. That's partly why the USA has gotten so good at parallel construction.