SAN FRANCISCO -- The California attorney general on Wednesday charged a private investigator with filing bogus documents to aid four death row inmates, calling the case one of the largest frauds ever perpetrated on the state's criminal justice system.

Kathleen Culhane was arraigned Wednesday afternoon in Sacramento on 45 felony counts of forgery, filing false documents and perjury.

"This is fraud at the highest level," Michael Farrell, a senior assistant attorney general, said after the arraignment. "This is someone who is trying to undermine the system."

Among the inmates for whom Culhane allegedly lied while working as a staff investigator for the Habeas Corpus Resource Center was Michael Morales, who was sentenced to death for the 1981 rape and murder of a Central Valley teenager.

Questions about the San Francisco private investigator arose a year ago when Morales petitioned the governor for clemency and prosecutors challenged the authenticity of several documents Culhane submitted on his behalf. His execution eventually was stayed over the state's lethal injection method, a matter unrelated to Culhane.

The attorney general's criminal complaint alleges that between November 2002 and February 2006 Culhane filed at least 23 fraudulent documents designed to aid Morales and three other death row inmates -- Vicente Figueroa Benavides, Christian Monterroso and Jose Guerra.

"She forged the signatures of those witnesses and jurors. Sometimes she completely made those documents up," Farrell said in court. "Her actions are an affront to the legal system."

Culhane's job was to find jurors and witnesses who may be favorable to the inmates and get them to sign declarations that could be used in their legal defense or requests for clemency.

Her paperwork was then turned over to the inmates' attorneys and filed with the courts and the governor. The counts against Culhane allege that she made up statements from real witnesses and jurors and forged their signatures, including six documents related to the Morales case.

In one instance, she submitted a declaration allegedly signed by one of the jurors who convicted Morales, according to a copy of Culhane's arrest warrant affidavit.

Investigators subsequently found that the juror never had been contacted by anyone working on the condemned man's behalf and that the document submitted by Culhane misspelled his first name as John, rather than Jon.

Culhane, 40, did not speak during Wednesday's court proceeding except to confirm her name in response to a question from the judge. Wearing an orange and white jail jumpsuit, she appeared behind a cage in a courtroom inside the Sacramento County Jail, where she had been held since she surrendered to authorities on Monday.

Her attorney, Stuart Hanlon, spoke in her defense after the arraignment.

"Ms. Culhane has a strong belief against the death penalty, and she devoted her life to fighting it by legal means," he told reporters.

Sacramento County Superior Court Judge David W. Abbott reduced her bail from $115,000 to $50,000 and set the next court date for March 22.

San Joaquin County prosecutors triggered the state's investigation of Culhane after they produced statements from jurors who swore they had never spoken with Culhane and supported the death sentence for Morales.

The Stockton man was scheduled to die last Feb. 21 for the 1981 rape and murder of Terri Winchell, 17.

The other three death-row inmates whose cases were affected by Culhane were convicted for crimes dating to the early 1990s: Guerra by a Los Angeles County jury for the 1990 rape and murder of Kathleen Powell; Benavides by a Kern County jury for the 1991 murder and rape of a 21-month-old child; and Monterroso by an Orange County jury for the 1991 murders of Tarsem Singh and Ashokkumar Patel and the attempted murder of Allen Canellas.

Those three remain on death row with pending appeals. Farrell, the state prosecutor, said Culhane's false documents will not affect the Morales case because they have been withdrawn but could delay the three other cases as investigators are forced to go back and interview jurors.

The attorney general's complaint alleges Culhane filed fraudulent documents under the names of 11 jurors, two witnesses, two court interpreters and one police officer.

She faces 22 counts of filing a false document, 22 counts of forgery and one count of perjury for signing a declaration falsely stating that she had met with a prosecution witness. If convicted on all counts, Culhane could face nearly 19 years in prison.

The Habeas Corpus Resource Center, a San Francisco-based agency that assists death row inmates, cooperated with the attorney general's office throughout the yearlong investigation and withdrew any declarations submitted by Culhane.

The state is continuing to investigate whether Culhane submitted fraudulent documents in any other cases, but authorities do not believe anyone has been released because of her actions.