The Bahrain Institute for Rights and Democracy said Mohammad al-Miqdad died Sunday at a hospital after being found unconscious on the street shortly after protests against the executions Saturday, AP reported.
The group said there were clashes at the protests with police firing tear gas, but that activists have been unable to verify the circumstances of his death.
Bahrain on Saturday executed two people convicted in two separate cases, one a case of “terrorism” and killing a police officer, and the second related to the killing of a mosque imam.
Human rights groups had been warning against the execution of Ali Mohamed Hakeem al-Arab and Ahmed Isa Ahmed Isa al-Malali.
Malali and Arab were convicted in a mass trial involving 60 people in January 2018. Both had exhausted all possible judicial appeals.
A last-minute appeal to stop their imminent execution was also issued by the UN special rapporteur on extrajudicial killings, Agnès Callamard.
Callamard said in a statement the men were tortured, prevented from attending their trial and sentenced to death in absentia.
Amnesty International Middle East research director, Lynn Maalouf, also warned the executions were “an utterly shameful show of contempt for human rights”.