A federal jury began deliberations late today in the conspiracy trial of ex-CIA agent Edwin P. Wilson after hearing a prosecutor brand as "hard-core hogwash" Wilson's claim that he was doing undercover work for the CIA when he arranged an illegal explosives deal with Libya in 1977.

After deliberating for four hours, the jury retired for the night.

Wilson, sentenced to 15 years in prison last fall on gun-smuggling charges in Alexandria, Va., faces up to 17 years if convicted here. He is charged with conspiring to ship 20 tons of high explosives from Houston to Libya in violation of U.S. export laws.

Arguments in the 10-day trial ended today with lengthy, often bitter closing statements by both sides. District Court Judge Ross N. Sterling repeatedly admonished Marian Rosen, one of Wilson's attorneys, to "stick to the facts of this case" in her remarks to the jury.

Both Rosen and chief defense lawyer Herald Price Fahringer stressed that Wilson was in Libya in October, 1977, when the shipment aboard a chartered DC8 cargo jet allegedly took place. They argued Wilson was unaware that alleged co-conspirators in the case intended to fly the explosives abroad disguised as oil field drilling mud in violation of U.S. customs and munitions laws, as the government charged.

"Doesn't the Bible say, 'If the trumpet gives an uncertain sound, who shall prepare for battle?' Doesn't this whole case have an uncertain sound?" Fahringer asked the jurors. "A free nation does not need the conviction of Ed Wilson on this impoverished, pathetic proof."

Assistant U.S. Attorney James Powers responded by characterizing the defense arguments as "90 minutes of hard-core hogwash."

Wilson "is not a patriot. He's a seller. He'd sell anything to make money," Powers said. The government charged Wilson's profit on the alleged explosives shipment totaled about $300,000.

Prosecutors also alleged that Wilson had tried to sell nuclear fuel and nuclear weapons to the Libyans. A former Wilson employe testified that Wilson hoped to "make millions and retire for life" on the weapons proposal, which was not completed.

"If you see an animal with a big nose, floppy ears and huge legs, you might say it's an elephant," Powers said, drawing an elephant on a courtroom blackboard. "But Fahringer and Rosen say, not so fast. Maybe it's a mouse with a glandular problem."

Fahringer, who argued at the start of the trial that Wilson was "a de facto CIA agent" while in Libya, feeding useful intelligence to his former agency employers, said today Wilson's ostensible agency ties formed a second defense to the charges he faces.

"Even if you find Wilson participated in this shipment," Fahringer told the jury, "if you believe Mr. Wilson was working with the CIA," it shows Wilson lacked the criminal intent necessary to return a guilty verdict. Powers derided that argument as a "multiple choice defense."

Earlier today, Assistant U.S. Attorney Theodore S. Greenberg was allowed to read to the jury a letter from CIA Executive Director Charles A. Briggs saying that a search of agency records had found no evidence the CIA was aware of or approved the alleged explosives sale to Libya.

The Briggs letter also said a search of the government's Interagency Source Registry failed to show that Wilson in 1977 was an agent of the CIA or any other U.S. agency. Wilson left the CIA Feb. 28, 1971, after a 15-year career as a spy, according to testimony here.

Judge Sterling overruled heated defense objections to the letter as well as attempts earlier this week to introduce testimony that the CIA allegedly has lied about use of secret agents in undercover operations.