The widow of a soldier who was shot to death about a week after his return from the Persian Gulf went free after a judge said there wasn't enough evidence to try her in the slaying.

District Judge Vesta Svenson ruled on Monday that the prosecution failed to show probable cause that Toni Riggs, 22, participated in the March 18 slaying of Army Spc. Anthony Riggs. Mrs. Riggs was released from jail.But Svenson ordered Mrs. Riggs' brother, Michael Cato, 19, to stand trial for murder. He was returned to jail without bail.

New charges could be brought against Mrs. Riggs if prosecutors come up with new evidence.

"There will, without question, be an appeal," Wayne County prosecutor John O'Hair said. "I believe there was enough evidence to sustain the charges."

The prosecution also is appealing a ruling by Svenson earlier this month that Cato's two confessions in the killings couldn't be used against his sister.

Police said Cato told them he and his sister plotted the slaying to collect on Riggs' life insurance. Cato also allegedly said he was the gunman. Mrs. Riggs could collect $175,000 in insurance as Riggs' wife.

Police initially believed Riggs was killed by a robber who made off with his car. The slaying had focused national attention on the dangers of random street crime versus the hazards of war.