There are a limited number of things someone who had been in prison for 2 - 5 years can do to legitimately be released from custody. Here are a few ideas:
1) Writ of Error Coram Nobis (discussed above) - newly discovered evidence that would likely change the outcome of the previous trial... this method gets the accused a new trial. These are often filed pro se (defendant represents themselves)
2) Writ of Habeas Corpus - an error was made at some stage of the proceeding that rendered the incarceration illegal... this often arises when a judge sentences the defendant erroneously to an illegal sentence or if there exists an error on the judgment documents that renders them void on their face. This method of relief will sometimes grant a defendant a new trial or simply a correction of a judgment by amendment.
3) Appellate process - Appeals in a murder case can easily last 2 - 5 years. Though not scandalous, her appeals could have found an error in the trial that gave her sufficient grounds to overturn the conviction. Again, this would result in a new trial.
4) Governor's pardon - The Governor of the State of California, through his pardon office, can pardon any state inmate and have them released immediately. This power is virtually unchecked.. though it is seldom used. Governor's pardons can be quite scandalous if they make the news and potentially could involve scandalous motivations.
5) Fake a mental health issue - if she wanted to challenge her conviction based upon her allegedly being incompetent to stand trial, she could do this by faking a mental health disorder and having attorneys challenge the conviction based on her lack of competency (criminal insanity and/or competency to stand trial). If successful on the criminal insanity issue, she could be transfered to a state mental health facility and potentially released upon successful rehabilitation. Incompetent to stand trial would only get her competency training and a new trial.
I'll keep brainstorming, but let me know if any of these sound good.