America’s professional association of psychologists has quietly declined to rebuke one of its members, a retired US army reserve officer, for his role in one of the most brutal interrogations known to have to taken place at Guantánamo Bay, the Guardian has learned.

The decision not to pursue any disciplinary measure against John Leso, a former army reserve major, is the latest case in which someone involved in the post-9/11 torture of detainees has faced no legal or even professional consequences.

Documents that emerged from a Senate armed services committee torture inquiry detailed Leso’s involvement in an early “Behavioral Science Consultation Team” at Guantánamo, which was instrumental in crafting torture techniques out of measures taught to US troops to withstand brutal treatment.

Leso is the latest case in which US officials involved with torture have escaped legal or professional consequences. A justice department investigation into CIA torture resulted in no indictments, and it never considered examining the architects of torture policy. Nor has torture caused its architects to suffer professionally: some have returned to tenured academic positions, awarded federal judgeships and sit on the boards of major corporations.

Doctors of the Dark Side exposes the scandal behind the torture scandal — how psychologists and physicians implemented and covered up the torture of detainees in US controlled military prisons. The stories of four detainees and the doctors involved in their abuse show how essential doctors have been to the torture program.