The mother of two Navajo men accused in the deaths of two tribal policemen angrily denied Saturday that she was providing an alibi to protect her two sons.

Lilly Atene testified in a rare weekend session in federal court that her sons, Ben Atene Jr. and Vinton Bedonie, could not have been involved in the killing of Navajo Officers Roy Lee Stanley and Andy Begay on Dec. 4 because they were with her at a "Blessing Way" ceremony in her hogan.Through a translator, the 59-year-old woman said, "I know they didn't do it. They were with me all night and didn't do anything."

When David Schwendiman, assistant U.S. attorney, asked her if it was difficult for her having two sons accused of murder, she answered, "Yes. They are here, and I want you to give them back to me."

Atene's sons and another Navajo man, Thomas Cly, are charged with shooting two officers and then burning them to death by torching their police trucks. The officers' charred remains were found in their burned trucks in isolated Copper Canyon south of Lake Powell on the Navajo Reservation.

Prosecutors contend the officers were killed after they tried to break up a drinking party near Monument Valley Hospital.

During the Saturday trial, Schwendiman accused Lilly Atene of asking medicine man Tall Litsui to tell police that her two sons were at a healing ceremony the evening of the slayings.

Lilly Atene became defiant, speaking rapidly in her native tongue. Obviously scolding prosecutors, a translator communicated her message: "I don't talk with the medicine man. It's you twisting my words, turning them around any way you want."

Insisting that her sons were at the healing ceremony - not at the beer party - she said her people obey their laws that have been passed down from their ancestors.

"You obey your laws and we obey our laws also," she said.

In response, Schwendiman quipped, "But sometimes we break the laws and that's why we're here."

The prosecutor's remark brought an immediate opposition from defense attorneys, and the comment was stricken from the record.

Lilly Atene's husband also testified that the two men were at the healing ceremony and, therefore, could not have participated in the brutal killings of the officers.

Earlier, the medicine man testified he conducted a healing ceremony that lasted from sundown on Thursday, Dec. 3, until sunrise on Saturday, Dec. 6. The officers were shot late the night of Dec. 4 or early the morning of Dec. 5.

Defense attorney Ed Brass called Harry Clark to the witness stand. Clark testified the third defendant, Cly, was not in the vicinity of the beer party the evening of the killings. Clark said he saw Cly "in a drunken state" near Clark's home in Oljato, San Juan County, during the early morning or late night of Dec. 4 and 5.

Inconsistency characterized the testimony of a 14-year-old relative of Vinton Bedonie. The boy was asked if he saw Bedonie the evening of Dec. 4.

At first he answered "yes." Then, when asked the question again, replied "no." And on a third round of questioning, he went back to his original statement, confirming he had seen him.

Defense attorneys say their clients have been charged based on gossip within the Navajo community. Testimonies are inconsistent because witnesses have been intimidated by the FBI and tribal police.

Because defense attorneys have subpoenaed more than 70 witnesses, the trial is expected to last at least another week. Proceedings were recessed until Tuesday.