Monday is last day of filing nomination papers for the 20 assembly seats where polling will take place on December 7.
Pahan filed his nomination from the Tamar assembly seat as an independent candidate. He was brought from the Hazaribagh open jail under tight security cover.
Jharkhand Mukti Morcha's (JMM) sitting legislator Vikas Munda has also filed his nomination papers from Tamar. He is son of former Minister Ramesh Singh Munda who was allegedly killed by Kunadan Pahan in 2008.
Kunadan is facing 128 criminal cases, including for the killing of Ramesh Singh Munda and looting Rs 5 crore cash from an ICICI Bank cash van in 2008.
The third candidate is former Minister Gopal Krishna Patar alias Raja Peter. Raja Peter is accused of conspiring to kill Ramesh Singh Munda and he allegedly paid Rs 5 crore to Kundan Pahan for doing the job.
AJSU President Mahtoi is in the limelight for not toeing the line of the ruling BJP and deciding to contest the assembly polls on his own.
The BJP and the AJSU have fallen out but none of the parties have officially announced a break up. The BJP and the AJSU have fielded candidates against each other in at least nine assembly seats.
Mahto filed his nomination papers from the Silli constituency which he had lost in the 2014 assembly poll.
Jharkhand Minister Nilkanth Singh Munda filed his nomination from the Khuti assembly seat.
The assembly elections will be held between November 30 and December 20 and counting will take place on December 23.
( With inputs from IANS )