Faisal held the position of an assistant director with the NAB, the country's anti-corruption agency.
The initial report has cited that the cause of Faisal's death was suicide. However, his relatives claim that he was murdered and are seeking a judicial inquiry.
His relatives alleged that torture marks were found on his body, which had also been shown to the media.
It has been reported that Faisal was under stress during the investigation of the RPP case and had requested to be recused from the probe.
Assistant commissioner (secretariat) Noman Yusuf has been named the inquiry officer to find out the reason behind Faisal's death.
NAB insiders told Geo News that Faisal, who had written the report on the case, was "mentally tortured" by senior officials to change the report but he refused to budge.
Faisal was assisting investigation officer Asghar Khan in a mega corruption scandal allegedly involving the prime minister.
He was one of the two officials suspended for recommending that the director general of NAB should submit references against the accused in the two RPP cases to the NAB's head office.