"We demand that accused in the violent attack on both journalists be immediately apprehended and the state government conduct an impartial inquiry in the matter," IWPC said in its statement.
Jagendra Singh, from Uttar Pradesh, died on Monday after a police raid on his home on June 1, following Facebook posts in which he accused local minister Ram Murti Verma of corruption.
The IWPC also demanded the state police to give protection to the family of the victims.
"If there is any threat perception to the families of the victims, given the nature of those allegedly involved, the state police should provide them with adequate security and protection," the IWPC said.
The IWPC expressed concern that journalists often are victims of violent attacks due to the nature of their work that involves risks and taking on people in positions of authority.