The court has fixed Saturday to pronounce the quantum of sentence in the case.
Beant Singh was on August 31, 1995, killed in an explosion outside Punjab and Haryana Secretariat.
Punjab Police official Dilawar Singh acted as a human bomb in the attack.
Tara had earlier three times confessed to the court: "I have no regret for killing Beant Singh."
In his confession, he has also said that Shaheed Udham Singh, who assassinated Lieutenant Governor of Punjab Michael O'Dwyer in 1919, was his inspiration to kill the Congress leader.
IMAGE: Jagtar Singh Tara