Pakistani authorities have opened a criminal investigation against jailed former PM Imran Khan on charges of leaking state secrets, after naming him and three aides in a fresh case, a top security source said on Monday. Khan is currently serving a three-year sentence in a graft case. “Our investigation is collecting evidence to stand a case in a court to indict Imran Khan on charges of leaking official secrets,” a security source, who is directly responsible for the investigation, said. Under the Official Secrets Act, a guilty sentence could range from two to 14 years in prison or even death.