Anand Mohan Singh comes from Pachgachhia village in Saharsa district, Bihar. He is the grandson of Ram Bahadur Singh, an Indian freedom fighter. His introduction to politics came through involvement with the Sampoorna Kranti movement of Jayaprakash Narayan, which caused him to drop out of college in 1974.
Singh claims to have begun his career as a violent criminal when he was aged 17 and that this was in response to the treatment of poor people by what he describes as "politicised criminals" in his native state of Bihar. The politics of Bihar has for many years been influenced by caste divisions, and Singh has been portrayed as a leader of the Rajput community in the state. Shifts in power, especially since 1990, have reduced the Rajputs, who are traditionally a ruling class, into a subordinate position.
Singh has made no secret of his resort to violence and his methods have been subject to investigation since at least 1978. It was around that time that he protested against the then Prime Minister of India, Morarji Desai, by waving black flags while a speech was being delivered. Around 1980 he founded the Samajwadi Krantikari Sena, which was among the first Bihari organisations intended to combat the rise of the lower castes. He was classed as an outlaw and rewards were offered for his arrest from time to time.
Singh served a three-month jail sentence in 1983 but in 1990 was elected from the Mahishi constituency to the Bihar Legislative Assembly as a representative of the Janata Dal (JD) party. He continued his criminal activities while a Member of the Legislative Assembly (MLA), leading a notorious sectarian gang, described by the Hindustan Times as a "private army", during the 1990s. The gang attacked people who supported reservation, which is India's system of positive discrimination for disadvantaged socio-economic communities. It ran riot until challenged by the rival gang of Pappu Yadav, at which time the situation in the Kosi area descended into a state akin to civil war.
When the JD appeared to be aligning itself in support of the Mandal Commission, which proposed to further extend the reservation system, Singh decided to break away. In 1993, he founded the BPP and personally contested and lost in three constituencies in the 1995 state assembly elections. The BPP later joined with the Samata Party, for whom he stood successfully in the Sheohar constituency as a candidate for the Lok Sabha (lower house of the Parliament of India) in the 1996 general elections. His success in those elections came despite him being in prison during the campaign. He was again elected from the constituency in the general elections of 1998 as a Rashtriya Janata Party candidate supported by the Rashtriya Janata Dal.
By 1999, Singh had switched the support of the BPP from the RJD of Lalu Yadav to the Bharatiya Janata Party. The BJP was courting him and numerous other criminal-politicians in Bihar as it sought support for the national government of Atal Bihari Vajpayee.
Singh lost his Sheohar seat to Anwarul Haq of the BJP in the 1999 general elections. Thereafter, he merged the BPP with the Indian National Congress (INC) and hoped to stand for election in Sheohar again, although the INC had other proposals for him.
Singh later joined Janata Dal (United) (JD(U)), although the relationship was strained at times. He is thought to have been a significant influence in the creation of the National Democratic Alliance government in Bihar headed by the JD(U) leader Nitish Kumar from November 2005, with his role being that of bringing together the Rajput and Bhumihar landowning communities. Singh was once again supporting the INC, and opposing Kumar, in the 2010 Bihar Assembly election, although he could not stand as a candidate due to being in jail.
Singh has had numerous charges filed against him at various times, many of which were either dropped or resulted in acquittal. He and six other people, including his wife Lovely Anand, were accused in relation to the 1994 murder of a Dalit district magistrate from Gopalganj, G. Krishnaiah, who was lynched on a major highway near to Muzaffarpur during a funeral cortege for the BPP member and gangster, Chhotan Shukla. In 2007, the Patna High Court sentenced him to death for the murder and abetting a crime. The sentence was reduced to rigorous life imprisonment in 2008, when the six other accused were also acquitted due to lack of evidence. The reduction was because there was no evidence that Singh was the actual assailant. In 2012 Singh failed in his appeal to the Supreme Court of India against the reduced sentence. The same Supreme Court hearing dismissed an appeal from the Government of Bihar for reinstatement of the death penalty and for an overturning of the acquittal of the six other people.
At the time of the original sentence in 2007, Singh was the first Indian politician since independence to have been given a death penalty. Soon after that sentence, upon being transferred from Patna's Beur jail to that of Bhagalpur, Singh went on hunger strike in protest of the facilities and being split from Akhlaq Ahmed and Arun Kumar, who had received death penalties in the same case. The jail authorities were unsympathetic, noting that rules dictated those sentenced to death should sleep on the floor and be allowed only simple food.
Despite being in prison, Singh aided his wife, Lovely Anand, whom he had married in 1991, in standing as an INC candidate in the 2010 Bihar Assembly elections and as a Samajwadi Party candidate in the 2014 general elections. The Supreme Court had barred convicted criminals from standing in elections but he still has much influence. She has claimed that her husband is the victim of a political conspiracy and has never been a criminal or gang leader.
People from his home village of Panchgachiya consider him to be a Robin Hood figure. Tehelka said in 2007 that
it was his muscleman image that made Mohan’s name synonymous with terror in Bihar’s poverty-ridden Saharsa-Supaul belt for the past 20 years. He and Munna Shukla faced several criminal cases, many of them for murder, in various courts across Bihar. While Shukla still remains a dreaded figure around Muzaffarpur and Vaishali districts in north Bihar, Mohan is notorious in the Saharsa-Supaul belt as a criminal and sometimes as a kind of folk hero.
He has written two anthologies of poems while imprisoned, Quaid mei Azad Kalam (Pen is free behind bars, 2011) and Swadheen Abhivyakti (2014). The inaugural ceremony of the books was held in the Constitution Club, New Delhi and was attended by various eminent personalities like Jaswant Singh, Rajiv Pratap Rudy, Bhim Singh, Navmber Singh.
In 2015, Central Board of Secondary Education (CBSE)added his short story on the life and struggles on Manjhi :the Mountain man to its eighth standard syllabus. The same has been made into a movie starring Nawazuddin Siddiqui and Radhika Apte.