On Combat
I met Lt. Colonel Dave Grossman in 2008 while lecturing on combat to cadets at the California Highway Patrol Academy.

Grossman is a retired US Army Ranger, paratrooper and West Point Psychology Professor and has written several publications on the subjects of killing, combat, interrogation, conflicts, terrorism as well as law enforcement culture.
One of the subjects I recall was the issue of interrogation and torture.
It was succinctly reflected in Gen. James Mattis response on the issue of waterboarding when interviewed for the position of Secretary Of Defense.
"I've never found it to be useful. I've always found, give me a pack of cigarettes and a couple of beers and I do better with that than I do with torture."
Like many warriors, my position was/is, 'whatever it takes to make them talk.'
In Grossman's book, 'On Combat' he points out that there are flaws and dangers in extreme measures. His position is not one of advocation but a well informed approach.
Grossman's book, 'On Killing" discusses the impact of killing on the individual.

On Combat. Available at Amazon
On Killing. Available at Amazon