In the wake of the hanging of Parliament attack convict Afzal Guru, global rights groups have asked India to end the use of executions and move towards abolishing the death penalty.
"Questions need to be asked why the Indian government executed Afzal Guru now," New York-based Human Rights Watch's South Asia director Meenakshi Ganguly said.
"No one argues that those who engage in serious crimes shouldn't be punished, but the death penalty is brutal and irreversible, and there is no convincing evidence to suggest it serves as a deterrent," Ganguly said.
The group said it opposes the death penalty in all circumstances as an inherently irreversible, inhumane punishment.
The hanging of Guru comes just three months after India executed the lone surviving 26/11 terrorist Ajmal Kasab in a Pune jail.
India should end this distressing use of executions as a way to satisfy some public opinion," said Ganguly.
"It should instead join the nations that have chosen to abolish capital punishment," she said.
Guru's execution makes it more urgent for India to reinstate its previous informal moratorium on executions as a step towards abolishing the death penalty, the rights group added.
Meanwhile, London-based Amnesty International has also expressed concern over Afzal's execution.
"We condemn the execution in the strongest possible terms. This very regrettably puts India in opposition to the global trend towards moving away from death penalty", said Shashikumar Velath, Programmes Director at Amnesty International India.
He alleged "serious questions have been raised about the fairness of Afzal Guru's trial. He did not receive legal representation of his choice or a lawyer with adequate experience at the trial stage. These concerns were not addressed".
"Before Ajmal Kasab's execution in November, Indian authorities used to make information about the rejection of mercy petitions and dates of execution available to the public prior to any executions. The new practice of carrying out executions in secret is highly disturbing," Velath said.
Guru was executed early Saturday for providing logistical support in the attack on the Indian parliament in December 2001, in which five heavily-armed gunmen entered the complex and opened fire indiscriminately, killing nine, including six security personnel, two parliament guards, and a gardener. All five attackers were also killed.