The men convicted in the murder of John Granville, of the U.S. Agency for International Development (USAID), and his driver, Abdurrahman Abbas Rahma, in 2008 escaped from prison in 2010 by digging a tunnel, The Sudan Tribune reported Thursday.
In a video posted last month on YouTube, the men said they dug a tunnel 125 feet long through a kitchen floor to outside the prison walls. Portions of the video were shot inside the prison in broad daylight and showed the tunnel.
The United States considered it "highly unlikely" the men pulled off the escape on their own, said the former official, who spoke on condition of anonymity.
While the United States had "great suspicion" that someone in the Sudanese government helped the men escape, they had no evidence, the ex-official said.
One of the escapees, Abdel-Ra'uf Abu-Zaid Mohamed Hamza, was later re-arrested by Sudanese officials. A second convict, Mohannad Osman Youssef, was killed in Somalia, his family said.
The U.S. government announced Tuesday it is offered a $10 million reward for information leading to the arrest of the two men still free, Mohamed Makkawi and Abdel-Basit Haj al-Hassan.