Raoul Moat said he would "take the shoot-out" rather than go back to jail, an inquest has heard.
The gunman was on the run from police following the shootings of karate instructor Chris Brown, his ex-girlfriend Samantha Stobbart and Pc David Rathband when he made the vow.
It was part of a message recorded by the gunman on a dictating machine three or four days before he was cornered by armed officers in Rothbury, Northumberland.
In the message, the 37-year-old said he had lost the only two people who mattered to him - his grandmother and Miss Stobbart - and he said if he returned to jail he would have "nothing to come out to" and that a shoot-out would mean "everybody's happy".
The message was read out to the inquest at Newcastle Crown Court by Superintendent Jim Napier, the Northumbria Police officer in charge of the criminal investigation into Moat's rampage.
Moat's half brother Angus, 41, told the inquest he was "shocked and stunned" by his brother's rampage. He said he "should have been involved" in the attempts to "talk Raoul down".
He said comments made by his mentally ill mother could have made his brother feel his family had turned against him.
He said: "My Mam had been to the press that week and had been on the front pages saying Raoul would be better off dead. I completely disagreed with that.
"Raoul thought everybody in his own family would be against him and I wanted to show him that was not the case. I thought if I could speak to him it could change the way he was feeling and the way he would act.
Angus and Raoul Moat's mother was "severely mentally ill and incapable of being a parent," the tax inspector told the inquest. Asked if his brother could have been similarly afflicted, Mr Moat replied: "Most definitely, I think he had an undiagnosed case of bipolar brought on by stress, being in prison, losing his business and his home."