Defendant Ben Atene Jr. joined in a fight with Navajo tribal policeman Roy Lee Stanley and helped to force him to the ground before the officer was shot, a federal district court jury was told Friday.

Atene is being retried on two counts of first-degree murder in the deaths of officers Stanley and Andy Begay following a hung jury in an August trial. Two other men, Thomas Cly and Vinton Bedoni, have received life sentences for the killings.Prosecutors believe the two tribal officers were shot during a Dec. 4, 1987, drinking party near Gouldings and then taken to Copper Canyon, where they were burned to death in a police panel truck.

The medical examiner who examined the charred bodies testified Thursday that both men were alive at the time of the fire, although he couldn't say whether they were conscious.

Marie Haycock, Mexican Hat, San Juan County, testified that she and others were at a bonfire near Gouldings following a Monument Valley High School basketball game and dance when Stanley drove up and told everyone to go home.

She said she saw Cly argue with the officer and then saw Cly, Atene and Bedoni punch and kick the policeman.

She said the three men forced Stanley to the ground, and a few minutes later, the officer was taken to his panel truck and shot. She did not see the actual shooting, but Bedoni had the gun in his hand, she said.

She testified that Cly then forced her to check the body to see if the officer was dead.

"I just said, `Oh my god, you've killed him,' but I don't know if he was dead or not," she told the jury. "I said that because I didn't want them to do anything more to him."

Haycock testified that Bedoni also shot Begay when he arrived to help Stanley, whom the men had forced earlier to call for help.

Defense counsel Loren Weiss questioned changes in the story Haycock has told in the months since the deaths. She admitted that in April she told an FBI agent several specific people had been at the bonfire but now is saying they were not, or at least that she's not sure. One of those was her uncle, Daniel Chee.

"So you just thought you'd implicate your uncle in this because the FBI asked?" Weiss said.

"Yes," Haycock replied. "I was scared and I was nervous and I didn't know what I was saying at that time."

She also testified that after leaving the scene of the bonfire, she and a cousin, Martha Chee, drove to a bar in Mexican Hat where they drank and danced, and neither woman tried to call the police.

Changing testimony was a theme of Friday's proceedings, with witness Julius Crank also admitting he had altered his story. He confirmed that he had told the FBI and a grand jury he had not gone to the bonfire, when, in fact, he had.

"I didn't really want to get involved in it, so I just said I didn't go," he explained.

Before adjourning the case until Tuesday, Judge Thomas Greene told jurors: "This is a case in which there are a lot of contradictions. This is a case in which there is an extreme necessity for jurors to be thinking about the credibility of witnesses" and all the reasons why testimony is given and why it may change.

The widows of the slain officers, Mary Lou Stanley and Laura Begay, testified Friday, tearfully identifying photographs of their husbands and describing the clothing the men were wearing when they went to work Dec. 4.