Kathmandu, Oct. 13 -- What initially appeared to be a day of spontaneous rage in Nepal is now emerging as a carefully planned campaign of destruction, according to a New York Times investigation into the September 9 arson attacks that left dozens of government and private buildings across the country burnt down.

The investigation - based on dozens of interviews, forensic assessments and field visits - found evidence suggesting that the nationwide fires, which erupted a day after 19 protesters were killed by security forces, were "too organized and too widespread" to have been a spontaneous reaction.

On September 9, fires consumed Nepal's key state institutions - including ministries inside Singha Durbar, the Supreme Court, and ward offi...