BY ALDO NAHED

At the same time that Ana Belén Montes was spying for Cuba from her desk at the Pentagon, she was also briefing Miami lawmakers about the tragic 1996 shootdown of four Miami fliers by an island MiG.

The revelation was made Sunday by Miami Republican Rep. Ileana Ros-Lehtinen during a news conference to announce publication of True Believer: Inside the Investigation and Capture of Ana Montes, Cuba's Master Spy, written by Scott W. Carmichael, the counterintelligence specialist who unveiled Montes' role as a Cuban agent.

Ros-Lehtinen told of her chilling recollection of Montes, as she stood next to the parents of Mario de la Peña, who was killed along with Armando Alejandre, Carlos Costa and Pablo Morales in the two Brothers to the Rescue planes.

''I remember after that terrible day in February, at an Intelligence Committee briefing in Washington, the person giving us all the information about Mario's death was Ana Belén Montes,'' Ros-Lehtinen said.

Before being detected in September 2001, Montes led a double life. She was a Pentagon senior Cuban analyst for the Defense Intelligence Agency and helped draft U.S. policy in dealing with Cuba.

At the same time, she passed secrets to Cuba, helping it to mount an effective counterintelligence.

Her apparent orders were to keep the Cuban government informed of classified intelligence, including data about the Feb. 24, 1996, attack on the two Brothers planes, according to the new book.

In the book, Carmichael says Montes' fingerprints are on other deaths.

He said she is partially liable for the killing of Army Sgt. Gregory A. Fronius, a Green Beret who died in a battle with left-wing Cuban guerrillas who overran a Salvadoran army camp in 1987.

Montes had classified knowledge of the secret army camp and had visited the camp days before Fronius was killed, he said.

Carmichael, whose job is to detect moles within the agency, said all book proceeds will go to the Fronius family of Sanford, N.C.

Sophisticated spies working for the Cuban government, like Montes, could be everywhere, lawmakers warned on Sunday.

Miami Republican Reps. Lincoln and Mario Diaz-Balart said aggressive measures need to be taken to find them.

''There are many Ana Belén Monteses, I believe, in other branches of the government of the United States, as well as in the private sector, in academia, in media, et cetera,'' Lincoln Diaz-Balart said.

Ros-Lehtinen said Montes likely helped Cuba for ideological reasons. ''She never received a dime from the Cuban government,'' Ros-Lehtinen said. 'She put our agents' lives on the line to satisfy Fidel Castro.''

Ros-Lehtinen said she and her fellow lawmakers are going to learn the extent of the damage Montes caused during a classified briefing in Washington on Thursday.

''She not only had access to the innermost U.S. government secrets, but she also created many of the assessments about what we know about Cuba,'' Ross-Lehtinen said.

Montes, born in Puerto Rico, was convicted of conspiracy to commit espionage for the Cubans and sentenced to 25 years without parole in a Texas prison.