Swiss national Oliver Rudolf Jufer pleaded guilty Monday to spray-painting over five portraits of King Bhumibol Adulyadej in Chiang Mai, and now faces a maximum 75-year prison sentence. The vandalism took place on Bhumibol's 79th birthday. The trial was closed to the public, and prosecutors declined to discuss details of the case because of sensitivities in Thailand about portraying the beloved king in a negative light. The military launched a separate investigation into the incident, saying that Jufer's act raised suspicion that he was hired by someone opposed to the Sept. 19 coup that ousted Thaksin Shinawatra, also a resident of Chiang Mai.