She asked the Board of Prison Terms for a fixed sentence and to be able to serve the remainder in Sweden.
Östberg, now 51, moved to California with her mother in the 1960s. As a teenager, she ran away from home and soon became a heroin addict. She married and attempted to stop her drug abuse. But when the marriage collapsed, she returned to her former lifestyle.
She then started a relationship with a drug dealer, Brian Cox. In April 1981, the couple argued with restaurant owner, Joe Torre, over money. Cox shot Torre dead.
The following day, they got a puncture and policeman Richard Helbush pulled over to help them. Thinking they were about to be arrested, Cox shot Helbush dead as well. The couple fled in the police car and were later arrested after a police pursuit and a gunfight. Cox hanged himself in his cell prior to the trial.
According to Californian law, Östberg is just as guilty as Cox, even though she did not pull the trigger.
Östberg was not hopeful in the run-up to the latest hearing. Her pleas had been turned down in 1997 and 2002. The fact that Cox killed himself, was crucial, since it left her to bear the burden of guilt. She also felt the presence of the murdered policeman's family would be decisive.
"Since the actual murderer took his own life, they want to lay all the blame on me. The murdered policeman's daughter can attend the hearing and speak against me. As long as a relative of the victims turns up on these occasions, I don't think I'll ever be released," she told Expressen.
During the hearing, Östberg attempted to convince the Board that she was remorseful and that she had changed during her 24 years in prison.
"I've been a liar, drug addict, prostitute and murderer. What happened stays with me every day, but I'm a different person now," she told the hearing tearfully.
As expected, Helbush's two daughters addressed the Board in highly emotional terms.
"You don't kill cops, you did that," said one.
"I hate you. I hope you stay here until you die," said the other, Tara Salizzoni.
The Chairman of the parole board, Margareta Perez, referred in her decision to the "cold-blooded" nature of the crimes and the "trivial motive".
"She continues to belittle the extent of her involvement," said Perez. Referring to the support Östberg has received from her native country, Perez said the Swedish press had given a one-sided view of her and recommended that she continue therapy.
Östberg has been the subject of high-level representations from prime minister, Göran Persson, and justice minister, Thomas Bodström. She's also received assistance from the Swedish consulate in Los Angeles and consul-general, Tomas Rosander, was extremely disappointed after the hearing.
"She had good references, but they were completely ignored. It was as if they didn't exist."
As a Swedish citizen, Östberg faces expulsion from the United States when (or if) she is finally released. Rosander had been hopeful that she would therefore be allowed to serve some of her sentence in Sweden.
"It would be good for her to have a transition period in a Swedish prison to allow her a better chance to acclimatise to a new country," he said.
Östberg's next chance to appeal is in 2008.