CHEYENNE, Wyoming (CNN) -- A trained sniper accused of gunning down his singer wife shot himself to death as investigators closed in on his hideout in Wyoming's remote back country, police said.
David Munis, a National Guard sergeant, was flown to a hospital in Laramie with a chest wound, Capt. Jeff Schulz said. He was pronounced dead at the hospital.
Albany County Sheriff Jim Pond said police were attempting to arrest Munis in connection with the death of his estranged wife, a singer who was shot to death on stage over the weekend.
"It was a self-inflicted gunshot wound as [an] arrest team was approaching him," Pond said. Munis was spotted by a ranch hand in rural Albany County, who tipped off the sheriff's department, and led investigators there on horseback.
A high-powered rifle and a pistol were found near Munis, Pond said.
Prosecutors had filed charges Tuesday accusing Munis of killing Robin Munis, 40, in a sniper-style shooting early Saturday as she sang at a Cheyenne restaurant.
Authorities found his black pickup truck late Monday in a remote area called Rogers Canyon, outside of Laramie. At least 40 officers had used dog teams and a Black Hawk helicopter in searching the area. The truck was in a police impound lot, authorities said.
Schulz said earlier that authorities found a handwritten message pinned to the wall at David Munis' home, apparently written before the shooting of Robin Munis, that was "near-confessional in nature."
"It does not come out and say, 'I did it,' " Schulz said. "It just very clearly points in that direction."
The note, which according to court documents was addressed to "everyone," also gives "a number of reasons why [the shooting] was going to happen," Schulz said.
Robin Munis was gunned down from a distance as she was on stage singing at the Old Chicago Restaurant.
"This part of her head was just, was absolute -- was gone," said Ty Warner, who was performing next to her. Watch bandmate Ty Warner describe how Robin Munis died »
Witnesses told authorities they heard a "pop" or a shot fired and saw a dark pickup truck speeding away from the area, according to a probable-cause affidavit filed in the case. Investigators found a bullet hole and damaged glass in a door of the restaurant, the affidavit said.
"The trajectory of the bullet was in line with where the victim had been standing ... and the bullet was recovered from a doorjamb behind the victim," documents said.
The bullet, a 7-mm., appeared to have been fired from a high-powered rifle and "was executed with precision. The shot was made from a distance."
David Munis, 36, had extensive military sniper training and was proficient in the use of high-powered rifles, the affidavit says.
Military officials told CNN he was a staff sergeant in the Wyoming National Guard and a decorated former Army sharpshooter who was trained at "sniper school" in Fort Benning, Georgia. That course includes wilderness survival and evasion tactics.
"The investigation revealed that David Munis owns approximate a dozen high-powered rifles equipped with professional optical scopes," the affidavit says. "One of these was described as a 7-mm firearm." That firearm has not been found, documents said.
The shooting came the day after police were contacted by Robin Munis, who told them she and her husband were in the middle of a divorce and that "he was frequently calling her and harassing her," the affidavit said. She also said he had been sending her "hostile" e-mails.
Police called David Munis, and he agreed to stop calling his estranged wife and use a third party for contact. Both parties also agreed to meet only at neutral locations, the affidavit said.
Schulz said David Munis did not make any threats to Robin Munis during the phone calls, but said the calls were frequent and she told police she did not want to talk to him.
Investigators found that a call was made from David Munis' cell phone to the Old Chicago Restaurant's business line at 8:54 p.m., a few hours before the shooting.
Authorities recovered seven "long guns" at David Munis' home, Schulz said.
David Munis' family, in Montana, has been "very cooperative," he said. His aunt told CNN her nephew had never been a violent person. She said she did not know Robin Munis. E-mail to a friend
CNN's Tracy Sabo contributed to this report.