Firstly, this is a tragic accident and my thoughts are with family and friends who have suffered a loss.
In reading through this thread, whilst it is always helpful to see healthy discussion over the likley cause of any accident - and in so doing hopefully avoid a repetition - I am concerned over any speculation as to WHO might be to blame.
Clearly, something went seriuosly wrong here and questions need answers. Firstly, what happened? How did this happen? How can we avoid this happening again?
Until these questions are answered we will be no wiser. I am not familiar with CVT but , at 3 miles out the KR3 might reasonably have been turning finals and being in a banked left turnn would have had the approaching Cessna under his Straboard wing. Equally, the Cessna being established on the approach ( landing gear down), would have the KR2 obscured under the port wing.
Eyewitness reports the KR2 flying into the Cessna but it just as plausible that the Cessna descended into the KR2. Whatever the circumstances there was a fatal collision and neither aircraft saw the other until too late. There will be a reason their aircraft found themselves occupying same airspace - both perhaps in the belief that the other was elsewhere.
If the KR2 vanished under the port wing/engine of the cessna and the Cessna was blanked by the KR2 starboard wing in a left turn an accident of timing ( I guess 70Kts Vs 120Kts) might have easily resulted in the relative juxtapositions at 3 miles out.