No one is looking for the killer of Caylee Anthony or Nicole Brown Simpson either. Being acquitted does not mean "not-guilty". In Canada, unlike the US, we do not have double jeopardy and I believe the Crown can appeal an acquittal.
MOO
Yes the Crown can appeal a verdict here. It's actually one of the things I question about our system. The state has a lot of power and, when they want to, effectively unlimited resources. Perhaps we should be expecting the system to get it right the first time rather than retrying verdicts they don't like. IIRC an appeal is how Guy Morin got wrongfully convicted.