The High Court has termed the execution of Col Abu Taher through a military tribunal order in 1976 an "outright murder".
The full text of an HC verdict, which was released on Monday, also termed the military tribunal judgement "illegal".
Explaining their terming the execution as a "cold blooded assassination", the judges who passed the verdict said Gen Ziaur Rahman, the then chief martial law administrator, had decided to execute Taher much before the formation of the so-called tribunal.
It also directed the government to try those who were involved with the so-called trial, if any of them are still alive.
The verdict, passed by Justice AHM Shamsuddin Chowdhury and Justice Sheikh Md Zakir Hossain, was originally announced on March 22, 2011.
The two judges signed the full text on Monday.
Deputy Attorney General Amit Talukder told The Daily Star that the 198-page judgment was released after the judges signed it.
The judgement will be uploaded on the website later in the day.
In the judgment, the HC cited some portions of the book written by BNP leader Moudud Ahmed, saying that the then Gen Ziaur Rahman had formed the military tribunal to sentence Col Taher to death in order to satisfy army officials who had returned from Pakistan.
Earlier on March 22, declaring the military tribunal and the trial illegal and unconstitutional, the HC said the trial and execution of freedom fighter Col Abu Taher in 1976 was masterminded by the then chief martial law administrator, Gen Ziaur Rahman.
Col Taher was a sector commander during the 1971 Liberation War of Bangladesh.
His supporters say he had a role in the soldiers' uprising on November 7, 1975 that saw Ziaur Rahman's release from confinement in Dhaka Cantonment.
Taher was later arrested and put to trial by a military tribunal that sentenced him to death on charges of mutiny and treason. He was executed on July 21, 1976.
Sixteen others including politicians Sirajul Alam Khan, ASM Abdur Rab, Maj (retd) Zia Uddin, Hasanul Huq Inu, Sharif Nurul Ambia, and Mahmudur Rahman Manna were also tried on the same charges and sentenced to various jail terms.