CHEYENNE, Wyo. - Police say they told a National Guardsman with sniper training to stop harassing his estranged wife hours before he is suspected of shooting her to death as she sang with a band in a restaurant and bar.

This photo released by the Cheyenne Police Department shows David Munis, 36, who is suspected of murdering his estranged wife Robin Munis, 40, early Saturday July 14, 2007 in Cheyenne, Wyo. [AP]

David Munis remained at large Sunday, a day after the shooting. The suspect, described by people who know him as a "big hunter" and an avid outdoorsman, may have headed for the woods, police said.

Robin Munis was shot in the head just after midnight Saturday as she sang with the classic-rock and country group Ty and the Twisters. Customers of the Old Chicago restaurant ran for cover.

"At first we thought it was just a speaker blowing up or something. I looked over and saw her on the floor," Travis Brooks, who had been sitting at the bar, told the Wyoming Tribune-Eagle.

Brooks said he wasn't sure where the gunshot had come from when he saw the glass door break. He and others crawled toward the kitchen and took cover in a small bathroom; others hid in a walk-in refrigerator.

The Munises had been separated for a few weeks, and Robin Munis, 40, had moved out of their home. On Friday, she called police after getting several harassing but non-threatening phone calls from her estranged husband, police Capt. Jeff Schulz told The Associated Press.

While an officer was at her home, David Munis called again.

"The officer picked up the phone in place of Mrs. Munis and just explained to him, 'Hey - can't do this,'" Schulz said. "He was very agreeable."

Witnesses saw David Munis in the area at the time of the shooting, though no one has reported seeing the shot fired, Schulz said.

The bullet that killed Robin Munis ended up lodged in a door frame. Police suspect it was shot from the parking lot behind the restaurant.

A search of the couple's home on Saturday turned up evidence tying David Munis to the shooting, Schulz said without elaborating. Police seized several guns but not the one used to kill Robin Munis, he said.

David Munis received sharpshooter training while in the active US Army. He has been in the Wyoming National Guard since 2003. He had no criminal record and was about to be promoted to second lieutenant in the National Guard.

"From all accounts, we've got a guy who had never been in trouble, was successful in the military," Schulz said.

Schulz said police were questioning David Munis' relatives in Montana and a friend at an Army base in Kentucky he had recently been in contact with.

Business at the Old Chicago was sparse Sunday. The shattered glass door had been covered with plywood, and a pool table was back in its spot at the occasional stage area.

Jim McBride, a partner in the restaurant, said that he was allowing his staff to return to work whenever they felt comfortable, and that grief counseling was available for them.

"We've got a couple kids who can't even walk into the building yet," he said.