In what’s setting up to be a self-defense case, California Valley murder suspect Gina Loret Mayborn told detectives that she gave Joseph King Cochran a verbal warning to “stop it” or she’d shoot him as he yelled and argued with his stepfather, her husband, Douglas Chadwick.

These and other details emerged from a recently released San Luis Obispo County Sheriff’s Office incident report.

“In a moment of clarity, I just knew that Cochran was going to kill my husband,’’ she told detectives.

Chadwick described his stepson as unstable on the evening of July 8 after Cochran, 49, threw a shovel at Chadwick from about 20 to 30 feet away, missing him by about 2 feet.

After Mayborn warned him, Cochran yelled back at Mayborn and moved toward a building that had more shovels. Mayborn then fired from a bedroom window after pushing out the screen, she said.

Mayborn described herself as a good shot and said she meant to hit Cochran’s shoulder. But the bullet struck his neck area. Cal Fire and paramedics later rendered medical aid, but Cochran didn’t survive.

“Mayborn said (to sheriff’s officials) she did the right thing by shooting Cochran and saving Chadwick’s life,” the Sheriff’s Office report states, noting that she thought it was a “sober decision and the right thing to do.”

“This has been a long time coming,” Mayborn told sheriff’s forensic specialist Jeanine West, according to the report.

At the conclusion of interviews with Mayborn, deputies arrested her on suspicion of murder.

Mayborn, 56, pleaded not guilty to murder on July 13 in San Luis Obispo Superior Court.

Chadwick told investigators that he and Mayborn had been together for about five years, since the death of Cochran’s mother.

On the day of the shooting, Cochran was agitated his ex-girlfriend had called Mayborn and that Mayborn had agreed to assist in pulling her new boyfriend’s vehicle out of a place where it was stuck, Mayborn told investigators. But it’s unclear if that was the focus of the argument.

Chadwick said Cochran made numerous threats in the past to kill him and Mayborn, and stated that he was going to run them off the property, the report said.

Mayborn cited three previous events of aggression with Cochran, though none were reported to law enforcement, according to the report. Cochran lived in a trailer next to where Mayborn and Chadwick resided on Dorris Road off Cucamonga Trail.

Asked whether she had anything to drink, Mayborn said she had a beer with dinner before the shooting and three beers after firing the single gunshot with a 20-gauge shotgun.

Deputies responded to the incident at about 8:40 p.m. after Cal Fire officials had begun working to save Cochran.

When deputies first spoke with Mayborn, she was hard to follow and continually changed subjects, but they were able to gather some information.

Investigators spoke with her a second time later that night.

When Mayborn appeared in court last week, she kept her head down and eyes closed until her case was called, then she stood and addressed Judge John Trice with her lawyer, Earl E. Conaway III, by her side.

“My client is ready for her day in court,” Conaway said in a telephone interview Thursday. “When that day comes, we’re confident the evidence will show that she’s not guilty of these charges.”