Shortly after 2 a.m. on April 19, the 21 year-old Anchorage man held a handgun to his left temple as he stood in the apartment he shared with his girlfriend, Brittany-Mae Haag. She attempted to grab the gun and stop him from taking his own life, prosecutors believe.
Police would later find both Sibson and Haag lying on the floor with gunshot wounds, and only one shell casing on the ground, Assistant District Attorney James Fayette told The Washington Post. Prosecutors believe the bullet that struck Sibson in the head - just behind his left eye - then hit Haag in the chest as she reached over to him.
Fayette, who has been a prosecutor in Anchorage since 1993, said he has never seen a "one-shot" case such as this one.
"It's just compelling and tragic all the way around," he said.
After the shooting, Haag, 22, managed to walk to neighbor's door to ask for help. The neighbor, Gary Hutson, followed her back to her apartment, cracked the door open and saw Sibson lying on the floor as Haag faltered, he told a local television station.
"How do you cope with watching someone's last moments?" Hutson said to KTVA.
Haag died later that morning as Sibson was treated for life-threatening injuries. He ultimately survived, and was released from the hospital within a couple of weeks, the district attorney said.
Sibson was cogent enough to speak to authorities a week after the incident. He told police he remembered buying the gun, but did not remember anything about the shooting itself, the prosecutor said.
Authorities said his blood alcohol level was more than three times the legal limit at the time of the incident.
Last week, Sibson was charged with one count of second degree murder on the grounds that he showed "extreme indifference to the value of life."
A grand jury indicted him, and a warrant was issued for his arrest before he turned himself in Friday. If convicted, Sibson could face up to 99 years in prison. Bail has been set at $250,000.
A judge on Sunday entered a not guilty plea on behalf of Sibson, KTUU-TV reported. Sibson wore a helmet covering his injuries during the courtroom appearance.
He told the judge that he is unemployed and could not afford a lawyer.
"Could we figure out if I'm guilty or not today?" he asked the judge, KTVA-TV reported.
Haag's family said in the first weeks after her death, they thought Sibson had intended to kill her.
"I was hurt because Victor has been part of our family," Sheila Lopez, Haag's mother, told KTVA. The couple were high school sweethearts. "He called me mom."
Hearing authorities have a new theory, Lopez said, "now it makes sense to me."
"Knowing my daughter, I would do the same thing, too," Lopez said. "If someone was trying to kill them self, I would go and try to stop them, and I know that that's what she would do."
But, Lopez added, "I'm very angry. That anger will never go away."
Chelsea Hartman, Haag's sister, told the TV station she is still struggling to understand how a bullet could have entered one person before killing another.
"I think a lot of it is still hard to grasp of how is it just one bullet, you know?" Hartman said. "It's just not fair."
Hartman added that the couple "always seemed happy."
"Always hugging, always kissing," Hartman said. "There was no greater love than what they had."
In an obituary, Haag's family called her death "a senseless act of violence which forever changed the lives of many." Family members KTVA they were able to harvest some of her remains, and donated her skin to burn victims affected by a major Anchorage apartment fire.
Haag was born and raised in Alaska and spent her time sledding, camping, fishing and rallying on four-wheelers, "a true 'lil Alaskan girl that got muddy, rode bikes and enjoyed the trampoline," the obituary stated. She loved taking care of rescued animals and dreamed of becoming a veterinarian's assistant. She had a very large and close extended family, and enjoyed spending time with them.
"Brittany was known for her strength, generous side and her heart so full of love for life, which was proven when we nearly lost her due to her Type 1 diabetes," the obituary stated. "Brittany was a fighter and did not let her condition slow her down, nor did it weaken her intoxicating smile."
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)