"Bhumibol Adulyadej ... chose not to condemn the 1976 massacre at Bangkok's Thammasat University of dozens of pro-democracy protesters ..."
Time Magazine: "Thailand Bids Farewell to Beloved King Bhumibol Adulyadej", regarding said events:
In early October of that year, demonstrations convulsed Bangkok in response to the arrest of prominent student activists. The crowd swelled to around 400,000, including many members of the public, owing to the military’s heavy-handed response that resulted in at least 100 civilian deaths. Bhumibol intervened, ordering the doors of Chitrlada Palace opened to provide the students refuge, and persuaded Thanom and his cohorts to go into temporary exile.
In September 1976, Bhumibol allowed Thanom to return to Thailand, even visiting him with Sirikit in Wat Bovornives — the Chakri dynasty’s personal temple — where he had ordained as a monk. Thousands of furious students gathered inside Thammasat University to oppose Thanom’s return. On Oct. 5, spurred on by radio broadcasts accusing the students of threatening the crown prince and communism, thousands of royalist paramilitaries massed outside the campus.
The killing began the following dawn. First, a rocket-propelled bomb was fired into the throng of students, reportedly killing four and injuring dozens. Military weapons wreaked a heavy toll until around 9 a.m., and at least two students were dragged out, tortured and lynched. Three others were seen dumped on tires, drenched in petrol and burned alive. A junta headed by the Defense Minister, Admiral Sa-ngad Chaloryu, seized power immediately after the massacre. Another flirtation with democracy had been crushed.
"New photos of 6 Oct 1976 massacre emerge" (NSFW, but apparently safe enough for the U.S. to consider Thailand among its staunchest asian allies for the past several decades):