A federal judge yesterday dismissed three tax-falsification charges against Dr. Murdock Head, the Airlie Foundation director who is on trial for allegedly scheming to bribe congressmen and other government officials.

With dismissal of the three tax counts, the Alexandria jury hearing the case against Head will be asked to render a verdict on only four of the 13 charges on which Head was indicted last July. The jury appeared likely to begin its deliberations today.

Head, 55, who is also a George Washington University professor and department chairman, remains charged with one count of conspiracy and three counts of tax evasion.

The conspiracy count -- the principal charge lodged against Head by the prosecution -- alleges, in part, that the Airlie director arranged to give $49,000 in bribes to Rep. Daniel J. Flood (D-Pa.), former Flood aide Stephen B. Elko, and former Rep. Otto E. Passman (D-La.) in exchange for their help in securing federal funds for his foundation, based near Warrenton, Va.

Judge Oren R. Lewis stated no reason publicly for dismissing the tax-falsification charges -- a ruling he announced after a lengthy private conference with prosecutors and Head's lawyers in his chambers. Previously, however, Lewis had expressed doubts that the counts could apply to Head since, the judge said, there was no evidence that Head himself had prepared the tax returns in question.

At issue are federal tax returns filed by Raven's Hollow Ltd., a film-making company linked with Airlie. The prosecution contends that Head arranged fraudulent deductions on the company's tax returns to reduce its tax liability.

Lewis previously had dismissed five counts alleging that Head gave an illegal gratuity -- an $11,000 loan -- to a former Internal Revenue Service agent in return for lenient tax treatment for his enterprises. Lewis ruled that the charges violated a five-year statute of limitations.

Lewis also set aside one count charging Head with giving Flood a $1,000 bribe in 1974. He ruled that Head's trial on this charge should be postponed until after Flood's retrial. Flood's first bribery trial ended in a hung jury last February, and Flood's second trial has been delayed because of his poor health.

Prosecutors declined to say yesterday whether they would appeal Lewis' dismissal of the gratuity and tax-falsification counts against Head.

Lewis announced his dismissal of the tax-falsification charges shortly before the prosecutors and Head's lawyers began presenting their closing arguments to the jury in U.S. District Court in Alexandria.

The court session ended abruptly as Brian P. Gettings, one of Head's attorneys, neared the conclusion of his closing statement. Gettings unexpectedly sat down, said he could not continue and urged that the jury be excused. Later, Gettings said he suddenly had felt palpitations in his chest and had become "light-headed," but he added, "I'm okay."

If gettings' health is not endangered, he will complete his closing argument today. The prosecution is expected to offer a brief rebuttal and Lewis will give the jury instructions on how to weigh the evidence before sending it out to consider a verdict.

Earlier in the day, Gettings had engaged in an angry exchange with Lewis. In the presence of the jury, Gettings accused the judge of "cutting off a relevant line of defense" by preventing him from eliciting testimony from Elko, that testimony, Gettings asserted, would show Elko had sought to extort money from Head.

Elko, who was a key prosecution witness, had been called back to the witness stand by Gettings. The lawyer, however, decided not to question Elko after Lewis' ruling.

Lewis replied to Gettings' assertion declaring "You certainly better not ever do that again." Then he sent the jury from the court room and accused Gettings of "deliberately" making an improper statement.

"You can make any charge you want against me," Lewis said. "But you cannot do it in front of these jurors."

In their closing arguments, the prosecutors and Head's lawyers offered sharply conflicting versions of the testimony and evidence presented during the six-day trial.

Assistant U.S. Attorney Joseph A. Fisher III denounced Head as a "master conspirator" and a "tax cheat," who had manipulated financial records to create a "slush fund" that was used for payoffs to congressmen. Other evidence, Fisher asserted, showed that Head later "was preparing to cover his tracks" to avoid prosecution.

Gettings attacked the prosecution's evidence as "a sham" and contended that Head had engaged only in legitimate activities. At the time Gettings abruptly broke off his argument, he was denouncing Elko's testimony about receiving payoffs from Head as "fabrications" concocted by a "convicted perjurer."

On three ocasions when Elko allegedly was given bribes by Head, Gettings said, Airlie's records showed Head was out of town. The alleged meetings could not have taken place, he said. Dr. Head wasn't even there."