Prosecutor John Keker's cross-examination of Oliver North has become a tense courtroom showdown between an ex-Marine who stands accused and an ex-Marine who is making the accusations.

North, the retired Marine lieutenant colonel on trial for 12 felony charges, did not even exchange the ritual pleasantries Tuesday with Keker, the smooth San Franciscan who is chief deputy to independent prosecutor Lawrence Walsh.The atmosphere was hostile from the start, as North refused to even acknowledge Keker's "Good morning, Colonel North."

Instead, as Keker's examination unfolded, North was by turns forgetful and combative, and the prosecutor was both needling and demanding.

North and Keker were Marine second lieutenants in Vietnam. North retired in May; Keker left the service and started a San Francisco law firm.

Testimony Monday and Tuesday produced these developments:

-Barely controlling his disdain for the prosecution, North testified that his White House bosses knew he was privately raising money for the Nicaraguan Contra rebels.

But Keker didn't buy North's reasoning.

North offered little more than one-syllable answers when Keker asked about his ethical and philosophical training as a student at the U.S. Naval Academy and in 20 years as a Marine Corps officer.

"You're trained to obey all lawful orders?" asked Keker.

"Yes," North replied.

"In fact, you take courses in this at the Naval Academy, right?"

"Yes."

"You learned that after World War II, German officers said they were just following orders and you were trained that that wasn't a defense, right?"

"Yes," the defendant said, adding finally, "I don't believe I ever received an unlawful order."

Keker pointedly asked if North told his White House superior at the time, national security adviser Robert McFarlane, about pitches he made to wealthy private Americans for donations to the Contras in 1985.

"I didn't need to talk to (McFarlane) much because he generally knew what I was doing," North said. Using McFarlane's nickname, Keker began, "Did you ever say, `Hey, Bud'?"

"I never called him Bud!" North shot back.

"Oh. What did you call him?" Keker asked. "Mr. McFarlane," North replied.

-Keker charged that North used his "good offices" to help co-defendant Richard Secord get a half-million dollars for renting a ship to the CIA.

North said that, acting on behalf of Secord, he offered the Danish-registered ship Erria to the CIA, which eventually turned down the offer.

"He could make for renting this ship as much as $500,000," Keker asserted.

"And that is totally separate from any (situation involving) me," North retorted.

-North again pointed to former CIA Director William Casey as the shadowy force behind his clandestine work to aid the Nicaraguan Contra rebels.

"The late William Casey?" Keker remarked, emphasizing the word "late." Casey died in May 1987.

"Yes, and if the late William Casey, God rest his soul, were alive, he'd be here to testify to it," North fired back.

"You bet he would," retorted Keker.

-North again asserted that he destroyed the ledger which tracked the money in his office safe on orders from Casey - and that he did not use the money personally. North is accused of converting $4,300 from the office safe fund to his own use.

"You had gotten loose," Keker snapped.

"I hadn't gotten loose," North snapped back. "I was working my tail off."

"You had loosened up the standards," said Keker.

"You said that. I hadn't," insisted North.

-North said he did not keep close account of a purportedly U.S.-controlled Swiss bank account set up by arms dealer Richard Secord to funnel donations to the Nicaraguan Contra rebels.

"You had no idea what was going into that account," Keker said. "They could have been spending it on dancing girls for all you knew."

"I trust that they were not," said a tight-lipped North.

-A disgruntled North admitted that he knew it might be wrong to accept a $14,000 security system from Secord, but he was angry the U.S. government refused to protect him.

North testified that it was "the one thing that didn't look right" about his role in the Iran-Contra scandal, and eventually covered up his non-payment with phony letters and bills.

"It has to be one of the dumber things I've done in my life," North said.

"Why didn't you pay for it?" asked Keker.

"I don't know," North said at first, then added: "I had come to the conclusion, having been fairly well trashed, I was kind of angry at the government. In the Marine Corps, they would have looked after me a little better than the place where I was working."

In another development late Monday, the Justice Department accused North of trying to terminate his 8-week-old trial with a sweeping demand for state secrets about U.S. efforts to free U.S. hostages in Lebanon.

North's lawyers filed a sealed request last week with U.S. District Judge Gerhard Gesell asking for subpoena power to demand documents about wiretaps of foreign nationals involved in the secret negotiations.

In court papers filed Monday, Edward Dennis, chief of the Justice Department's criminal division, accused North of launching "a last-ditch effort to use classified information as a weapon rather than as proof."

The charges against North include lying to Congress, destroying official documents, tax fraud and accepting an illegal gift. If convicted on all counts, he faces 60 years in prison and $3 million in fines.