[2][3][4] Singh was born in 1959 in the village of Chaheru to a Badwal Saini Sikh family, Kapurthala, Punjab.
He then moved to the home of his maternal aunt Niranjan Kaur, in the village of Kala Bakra, for his secondary education.
On 18 June 1983, Chaheru and an associate shot dead chief of Criminal Investigation Agency Phagwara Inspector Rattan Chand Sharda in his office.
[24] Mabir Singh Chaheru was not inside Sri Harmandir Sahib (The Golden Temple) during Operation Blue Star in 1984.
[26][27][28] Mabir Singh set up the KCF military hierarchy, but ad hoc groups conducted most operations at the local level.
According to police 6 men in a jeep opened fire on the escort of Kabul Singh and a policeman.
[34] On 26 March 1986, KCF members killed Arjan Singh Mastana an MLA and leader of Communist Party of India.
[39][31] 6 officers were killed, and more injured, in a violent attack on the District court in Jalandhar, Punjab, India which broke free Labh Singh, and others.
[47] The Courier of Arizona, US, carried a story attributed to UPI stating that 3 "Sikh terrorists" killed 3 police officers who were taking 3 prisoners to a bathroom, while "16 armed court guards cowered in fear".
The report stated that 2 police holding a 4th prisoner were also gunned down, and that "Three other officers, a lawyer, and a bystander were wounded as the Sikhs sprayed the area for 15 minutes."
Finally, the Courier article reported that the Sikhs looted "three rifles and a submachine gun" from the dead bodies, and that a 6th officer later succumbed to wounds from the attack.
[48] The Wilmington Morning Star carried an AP story, and related that 3 "Sikh extremists" killed 4 police officers inside the District Court complex, killed two officers who "were shot at the courtyard gate as the attackers fled", and wounded 4 other individuals, including a lawyer.
The Star reported that District Magistrate S.C. Aggarwal said 4 attackers fired over a compound wall from a lane.
It further reported that others witnessed the attackers open fire from close range as police led the prisoners to the toilet.
Once they went, Chaheru and his partners opened fire on the policemen, the attackers killed 4 police officers inside the court complex and 2 at the courtyard gate.
[54] On 15 July 1986, Manbir Singh organised an attack on Karpurthala Jail to rescue 2 Sikh militants.
[55][56][57][58] In 1984, General Arun Vaidya had planned and supervised[59] Operation Blue Star – a controversial military operation ordered by Indira Gandhi, then Prime Minister of India,[60] in order to flush out a group of heavily armed Sikh militants in June 1984 at the Golden Temple, the holiest shrine of the Sikhs.
On 10 August 1986, General Arun Vaidya was shot and killed by Jinda and Sukha while he was driving his car home from the market.
[63] According to Indian intelligence sources, Vaidya had been the number four assassination target on lists by Sikh militants and he was one of several people killed in retaliation for Operation Blue Star.
[64][65] Following the assassination, the Khalistan Commando Force issued a statement declaring that Vaidya had been killed in retaliation for the Operation Blue Star.
[66][67][68][69][70][71][72][73] Punjab police stated that there were two dozen murder cases registered against Chaheru by that time.
In the city of Chandigarh, the Punjab Police Chief Julio Francis Ribeiro told news reporters afterward that "...they do not need to worry as Manvir Singh will not come back.