For all that I was otherwise occupied, I found where I'd read it (surprisingly fast), and the source used:
http://www.virginiacops.org/articles/shooting/combat.htm About some study conducted by the NYPD, apparently.
It has been assumed that if a man can hit a target at 50 yards he can certainly do the same at three feet. That assumption is not borne out by the reports.
An attempt was made to relate an officer's ability to strike a target in a combat situation to his range qualification scores. After making over 200 such comparisons, no firm conclusion was reached. To this writer's mind, the study result establishes that there is indeed a disconnect between the two.
If there was a connection between range marksmanship and combat hitsmanship, one would expect the combat hit potential percentages, to be well above the dismal ones reported. That is because the shooting distance was less than 20 feet in 75 percent of the 4000 encounters studied.
The element reported as the single most important factor in the officer's survival during an armed confrontation was cover.
In a stress situation an officer is likely to react as he was trained to react. There is almost always some type of cover available, but it may not be recognized as such without training.
And, twice while I was trying to copypaste that, this tab decided I was no longer using it, and cleared itself from memory.