A photo obtained by CNN shows bin Laden (center) with two unnamed colleagues

From Correspondents Peter Bergen and Henry Schuster

WASHINGTON (CNN) -- Two sons of an Egyptian cleric convicted of plotting terrorist attacks in New York City have joined the terrorist organization of Osama bin Laden, which is suspected of carrying out deadly bombings against two U.S. embassies in east Africa, CNN has learned.

Sheik Omar Abdel-Rahman, serving a life sentence in a federal prison, also has written a will calling on his sons to seek revenge against the United States, according to sources who have seen it.

The ties between Abdel-Rahman and bin Laden are the subject of an investigative report on Sunday's "NewsStand: CNN & Time," at 10 p.m. EST.

In 1996, Abdel-Rahman and nine co-conspirators were sent to prison for plotting to bomb the United Nations, FBI headquarters, two tunnels and a bridge connecting New Jersey with Manhattan -- all in one day. Authorities believe the group also was involved in the 1993 bombing of the World Trade Center that killed six people and injured more than 1,000.

Abdel-Rahman's two sons, Omar and Asim, both in their late 20s, were among those present when bin Laden held a press conference near Khost, Afghanistan, in May.

It was at that press conference that bin Laden publicly unveiled his International Islamic Front and talked about an edict he issued in February, calling for a jihad, or holy war, against American civilians anywhere in the world.

A person who spoke to one of Abdel-Rahman's sons told "NewsStand" that "he said that he would follow into the footprints of his father and he would continue the jihad."

The U.S. government believes bin Laden carried out the threats he made in Khost by ordering the August bombings of the U.S. embassies in Nairobi, Kenya, and Dar es Salaam, Tanzania, which killed more than 200 people.