In April 1979, three months after the Ayatollah Khomeini made his triumphal entry into Tehran and the vicious tenor of the new regime had become clear, 10 men, some of them pro-shah and others simply anti-Khomeini, gathered in a suburban Maryland home to discuss what they could do.

Out of those informal discussions was born the Iran Freedom Foundation, dedicated to toppling the Khomeini government and publicizing what they saw as astrocities being committed by the radical Moslems who had taken over Iran.

At its head, from the beginning, was Ali Akbar Tabatabai, 49, who was shot to death yesterday at his home, which also served as the headquarters for the foundation. Yet, in keeping with the rampant paranoia that has come to haunt Iranian expatriates around the world since the revolution it was at once public and intensely secretive.

Only Tabatabai was willing to let his name be attached publicly to the foundation. Only Tabatabai was eager to go before television cameras and radio microphones to discuss the positions of the foundation. In the end, said one of the original 10 who asked that his name not be used, their fears for the safety of their families and themselves were borne out by what happened to Tabatabai.

"Now I don't know what we'll do," said the man. "We will have great difficulty in finding someone as brave and dedicated as Tabatabai to do what must be done."

Tabatabai was president of the foundation as well as its spokesman. Because of his prominent public profile, the Iran Freedom FOUNDATION (IFF) became in turn the most widely known of nine anti-Khomeini groups in the United States.

The agenda for the IFF was set at the beginning, according to the member.

"Our object was primarily to expose the true nature of Khomeini," he said, "to point out the terrible things happening in Iran, to inform the Americans of the problems facing the Iranian people and to unite the Iranians overseas, especially in the United States."

In all cases, it was Tabatabai who took the public stage. The 10 members, who included former government officials and military men under the shah, intellectuals who opposed the shah and the Khomeini regime, and Iranian businessmen here in the United States, were regularly in contact by phone, discussing new plans or tactics. But apparently it was always Tabatabai who implemented them.

He appeared on talk shows, both radio and television, locally, nationally and in Canada. He helped organize a major anti-Khomeini demonstration in Los Angeles earlier this month, designed to bring together the different anti-Khomeini groups.

He was also organizing a followup demonstration in Washington for this coming Sunday. As planned by Tabatabai, it was scheduled to begin at 1 p.m. on the west Capitol steps, and to include a march down Constitution Avenue and a demonstration in Lafayette Square in front of the White House.

"Everyone I have talked to," said another Iranian, a former official in the embassy before the revolution, "is saying that now we must all go out there and demonstrate. We cannot let these people keep us from opposing them."

The prominence of the IFF gained it a sizable following, the member said. "We have a mailing list of about 4,000 people around the country, and we get our funds from, them," he said.

But many of the other anti-Khomeini groups see the IFF as "a pain of the -- ," said one Iranian expert; who like nearly everyone interviewed yesterday asked not to be identified. "The other groups consider themselves more moderate. They feel the IFF is more pro-shah than anti-Khomeini."

The IFF members denied that charge and several others that have been leveled at the foundation.

The death of Tabatabai has left the IFF a shambles, the member said. "We don't know what we'll do. We will have to talk about it in the future, after everyone gets over the shock."