Former Arunachal Pradesh chief minister Kalikho Pul allegedly committed suicide on Tuesday. He was found hanging at his residence in Itanagar.
Pul's close aides said the rebel Congress leader was suffering from depression. However, a probe has been ordered to find out what drove him to take the extreme step.
Pul was at the centre of a rebellion against the Congress government, which resulted in the imposition of the President's rule on January 26 this year.
With the support of 18 dissident Congress lawmakers, two independents and 11 BJP lawmakers who gave outside support, in the 60-member assembly, Pul was sworn-in as the chief minister on February 19.
In July, however, the Supreme Court ordered Pul to step down, while reinstating the Nabam Tuki-led government. A five-judge Constitution bench, led by Justice J.S. Khehar, had termed the Centre's attempt to bring the state under its direct rule by overthrowing an elected government as "illegal".
However, in order to stabilise the party and bring the rebel leaders back into its fold, the Congress decided to replace Tuki with Pema Khandu to head the government.