BY TIM JOHNSON

                      WASHINGTON - Even though confessed Cuban spy Ana Belen Montes already outwitted a lie-detector
                      test, the government plans to rely on polygraph exams to check her honesty as they debrief her about
                      her 16-year spying career while working for U.S. military intelligence.

                      Montes took a polygraph examination at least once during her career as an analyst at the Defense
                      Intelligence Agency, her attorney says.

                      ''At the time she was polygraphed, she passed it,'' said prominent Washington attorney Plato Cacheris,
                      who added that he did not know when the exam was given.

                      Critics of polygraph exams, which are designed to snare liars, say they are astounded that U.S. officials
                      would rely on them to determine if Montes is telling the truth.

                      ''Isn't this incredibly ironic?'' asked Drew C. Richardson, a retired FBI agent who wrote a doctorate
                      dissertation on polygraph research. ``She beats the polygraph and now we're going to use a
                      polygraph to assess the damage? It's utterly, unbelievably stupid.''

                      Montes, 45, is the most senior spy for Cuba ever caught. FBI agents arrested her Sept. 21 at her
                      workplace. In a plea agreement with the Justice Department, Montes confessed March 19 to spying for
                      Cuba and offered to reveal all details of her betrayal to investigators before her Sept. 24 sentencing. If
                      polygraph exams show that she has been honest and candid, she will get a 25-year jail term, with five
                      years of parole.

                      Montes isn't the first turncoat in the U.S. intelligence community to beat the polygraph, or lie-detector,
                      exam, and her case is sure to add to controversy over whether the government can rely on the
                      polygraph to catch spies.

                      Some critics assert that the polygraph tests lure counterintelligence units into a false sense of security,
                      and should be abandoned for other methods.

                      The Defense Intelligence Agency, which is the preeminent military intelligence arm of the Pentagon,
                      declines to say whether -- or when -- Montes was given a polygraph exam after her hiring in September
                      1985. It also refuses to provide details of results of any exams given to Montes.

                      ''All DIA employees are subject to polygraphs,'' said an agency spokesman, Lt. Cmdr. James E. Brooks,
                      declining further details.

                      REGULAR TESTS

                      All government intelligence agencies require employees to agree to regular polygraph examinations. In
                      such tests, an examiner asks a subject questions while a polygraph machine measures changes in a
                      subject's heartbeat, blood pressure and respiratory rate. If the subject lies, the theory goes, then the
                      examiner can detect faster heartbeats, higher blood pressure and other telltale physiological changes.

                      The FBI, the CIA, the National Security Agency, federal and state governments, local police departments
                      and numerous private agencies routinely use polygraph tests to detect suspected criminal activity.

                      ''The use of polygraph is controversial even within the law enforcement and intelligence community,''
                      said John L. Martin, the former head of internal security at the Justice Department.

                      Some form of polygraph machines have been around since 1917, and their use is now widespread,
                      even if still controversial. ''There may be about 3,000 examiners [in the United States],'' said Dan
                      Sosnowski, a spokesman for the American Polygraph Association, a trade group.

                      In 1988, Congress barred most private employers from probing possible criminal activity of job
                      applicants through polygraph exams. Law enforcement agencies and some limited categories of private
                      companies can still require a polygraph exam as a preemployment requirement.

                      While statutes vary from state to state, polygraphs can sometimes be introduced as evidence at
                      criminal trials if attorneys for all parties agree, Sosnowski said. They are inadmissible in Florida courts
                      unless the prosecution and defense agree to admit them.

                      The CIA is known as the agency with the most-freewheeling polygraph tests, delving even into intimate
                      details of the lives of employees in an effort to unmask spies.

                      ''There's a schedule of polygraphs that you have over your career. And they can be aperiodic as well,''
                      said CIA spokesman Tom Crispell. ``It is one of many tools that are used at the CIA as a security
                      procedure.''

                      Curiously, among those criticizing the use of polygraph tests is Aldrich Ames, a CIA veteran arrested in
                      1994 and accused of receiving more than $2 million to reveal to the KGB the names of U.S. agents in
                      Russia. At least 10 agents were later killed.

                      PASSED EXAMS

                      Ames passed two polygraph exams in the CIA while spying for Russia, said one knowledgeable official,
                      speaking on condition of anonymity.

                      The polygraphs were not done correctly, he said: ``It indicated deception. They didn't pursue it.''

                      Ames calls the polygraph tests ``pseudoscience.''

                      ''Like most junk science that just won't die [graphology, astrology and homeopathy come to mind],
                      because of the usefulness or profit their practitioners enjoy, the polygraph stays with us,'' Ames wrote
                      in November 2000 from his cell at Allenwood federal prison in Pennsylvania.

                      ''The U.S. is, so far as I know, the only nation which places such extensive reliance on the polygraph. . .
                      . It has gotten us into a lot of trouble,'' Ames added in letter to a staff employee of the Federation of
                      American Scientists, Steven Aftergood.

                      Another career CIA analyst, Larry Wu-tai Chin, arrested in 1985 as a spy for Beijing, also beat the
                      polygraph exams he was administered.

                      Martin, the former chief counterintelligence officer, said the polygraph exam, if administered with
                      precisely phrased questions, can lead to new avenues of interrogation, and uncover deception.

                      ''It can be effective if used properly,'' Martin said.

                      Aftergood, the official at the Federation of American Scientists, said evaluation of polygraph tests ``is a
                      subjective matter.''

                      ''There is a widespread recognition that it is not an entirely reliable technology,'' Aftergood said.