PANAMA CITY, OCT. 5 -- Shortly after midnight last Dec. 24, Otilia Lopez de Perea went into labor. She was nine months pregnant, but her timing could not have been worse.

Four days earlier, thousands of U.S. troops had descended on Panama City, clinching a quick military victory. That Christmas Eve, as the 21-year-old Lopez de Perea drove to the hospital with her husband, mother-in-law and a neighbor, the city was still gripped by post-invasion jitters.

Flying a white flag, they stopped at a U.S. military roadblock on the Transisthmian Highway, where they requested an escort. They were told that with their white flag, no escort was necessary.

As they continued along the road, less than 500 yards later, troops at a second checkpoint opened fire on their Volkswagen, mistaking it for a hostile vehicle. Ten seconds later, the checkpoint's commander ordered a cease-fire, but it was too late.

Lopez de Perea and her 25-year-old husband, Ismael, were killed. The baby, the couple's first, was never born. The neighbor, who was driving, was hit in the stomach and hand but survived. The mother-in-law, uninjured, was hysterical.

In the chaos surrounding Operation Just Cause, the death of the couple was a little-noticed tragedy. From the U.S. Army, it merited a terse form letter denying compensation to the victims' families.

The U.S. Southern Command, which confirmed the facts of the case, said a review of the incident, "although tragic in nature, indicate{s} that the U.S. personnel acted within the parameters of the rules of engagement in effect at that time."

Nine months after the shooting stopped, nagging evidence of careless or indiscriminate killing of Panamanian civilians by U.S. troops continues to shadow the history of the largest U.S. combat operation since Vietnam.

The U.S. Southern Command's official death toll, released Jan. 11, says that the invasion and ensuing looting and chaos claimed the lives of 314 Panamanian military, 202 Panamanian civilians and 23 U.S. troops.

Some critics of U.S. policy in Panama have charged that casualties numbered 4,000 or more, but they have not produced any evidence to support their statements.

Nevertheless, many Panamanians as well as international human rights groups now believe that the Panamanian death toll included more civilians than members of the Panamanian military or paramilitary groups. Moreover, there are indications that the Southern Command may have over-counted the number of Panamanian military casualties.

"The military casualties were relatively low," said Juan Mendez, director of Americas Watch, the Washington-based human rights group. "There was very little resistance. These people didn't really fight. . . . I think the bulk of the dead were civilians."

The Pentagon generally has defended the conduct of U.S. troops in the invasion as disciplined and efficient. Virtually all allegations of troop misconduct have been dismissed, and an Army sergeant who was court-martialed on murder charges for killing a Panamanian at a roadblock Dec. 23 was acquitted last month.

In cases in which the army has acknowledged tragic errors, officials generally insist that troops fired warning shots before shooting to wound or kill. They stress that in the days immediately after the invasion, paramilitary groups called Dignity Battalions were still operating in the streets, snipers were taking potshots at U.S. forces and the atmosphere in the city was tense.

However, even some Panamanians who steadfastly support the invasion acknowledge the taint left by "mistaken" civilian deaths on the collective memory of Operation Just Cause.

"There are so many stories like this," said Michael Pierce, an American lawyer here representing Lopez de Perea's family and dozens of other Panamanians who lost relatives or property in the invasion.

Pierce says he is handling 32 cases of civilians mistakenly killed by U.S. troops at barricades. "None of them were armed, none of them were dangerous," he said. "They, the incidents, were just mistakes."

Among the claims Pierce is handling is the case of seven civilians who died in a Toyota mini-van at a roadblock near where Lopez de Perea and her husband died a couple of hours later. The Southern Command says troops fired on the vehicle after someone riding in it shot at them, adding that two handguns were found in the mini-van after the shooting.

According to the claim made on behalf of their families, however, troops opened fire on the van after they heard gunshots in the distance. The six men and one woman ranged in age from 17 to 25; they left seven children.

In another of Pierce's claims, Luis Alberto Riano and his wife, Grettel, drove their Volvo into Paitilla airport early Dec. 22 to check on their store there. U.S. Rangers, who had seized the airport in heavy fighting, opened machine-gun fire on the car and blasted it with an anti-tank weapon.

Riano was killed and his wife was injured. The troops say they fired warning shots; Grettel Riano denies it.

The question of whether the U.S. is obligated to pay reparations for civilian lives and property destroyed in the invasion has grated on relations between the two countries.

In a class action lawsuit filed in U.S. District Court in Washington last week, Panamanians harmed by the invasion asked that the U.S. Army adjudicate and pay claims to relatives and victims.

Another lawsuit by a group of businessmen asks $432 million for damage and theft from the looting that followed the invasion. Many Panamanians criticize U.S. military planners for failing to provide security in commercial areas of the capital after the invasion, leaving shops and stores defenseless against roaming bands of looters. But one Panamanian merchant compared the lawsuit to "suing the fireman who breaks down your door to put out the fire."

The Foreign Claims Act prohibits the payment of claims arising from U.S. combat operations. But the United States has made exceptions to that in the past, paying $1.8 million in claims to about 900 families in Grenada after the invasion of the Caribbean island in 1983.

"We're providing half a billion dollars in aid to the government there, and in our view that's enough to meet all the social needs," said an administration official, speaking on condition that he not be identified. "With the Dignity Battalions, the U.S. forces, generalized looting and what not, to enter into a claim-by-claim adjudication would be time-consuming at best. In a lot of these {cases} it's not clear you would have evidence to reach a resolution."

Panama's U.S.-installed civilian government, deeply dependent on U.S. aid to spur the country's economic recovery, has been nearly silent on the issue of claims against the United States for lost lives and property. "It's a giant against an ant," said one official. "We're keeping our mouths shut."

Human rights monitors and officials here say that while the U.S. military may have undercounted civilian fatalities, it probably overstated the number of Panamanian military deaths. The Panamanian Medical Legal Institute, the government's official coroner, told the Southern Command in June that it had identified only 63 military fatalities, as well as the remains of 157 civilians; 47 other bodies had not been identified.

Moreover, insurance claims from the families of Panama Defense Force members have provided another indication that military fatalities were relatively low. The families of soldiers killed in action are eligible for $5,000 payments through an insurance concern here. So far, 68 families have come forward to collect benefits, according to Tomas Valverde, assistant manager of the firm.