I dissent.
Unlike the majority, I would adopt the referee’s findings that inmate witnesses Raybon Long, Ryland Cade, and Rick Yacotis gave false testimony against petitioner at his capital trial, claiming that they saw petitioner stab inmate Charles Gardner or heard petitioner confess to the stabbing. (People v. Roberts (1992) 2 Cal.4th 271, 295 [6 Cal.Rptr.2d 276, 826 P.2d 274].) The referee’s findings are supported by substantial evidence and therefore entitled to great weight. Without the false testimony, there is a reasonable probability the jury would not have convicted petitioner of Gardner’s killing. (In re Sassounian (1995) 9 Cal.4th 535, 546 [37 Cal.Rptr.2d 446, 887 P.2d 527].) I would therefore grant the petition for writ of habeas corpus.
I. Background
On the morning of August 17, 1980, as Charles Gardner, an inmate at the California Medical Facility in Vacaville, was walking down a hallway lined with other inmates, he was attacked and repeatedly stabbed. Gardner retrieved a prison-made knife dropped on the floor and pursued two inmates who had fled up a stairway. Grievously wounded, Gardner reached the second floor where, before he collapsed and died, he fatally stabbed a guard, Albert Patch. Shortly thereafter, guards apprehended petitioner in his third floor cell and seized another inmate, Archie Menefield, just as he reached the third floor.
Petitioner and Menefield were tried jointly. At trial, various inmates testified that petitioner harbored ill feelings toward Gardner, stemming *748either from a recent incident in which Gardner insulted petitioner or from a power struggle within the Black Guerilla Family, a prison gang. Five eyewitnesses to the stabbing testified at trial. Inmate witnesses Long and Cade testified that petitioner was armed and waiting in the corridor, that he stabbed Gardner and then ran up the stairs. Inmates Cade and Yacotis testified that after the stabbing, while each was in a segregation unit near petitioner and Menefield, they heard petitioner admit to stabbing Gardner.
Petitioner was found guilty and sentenced to death for the first degree murders of Officer Patch and inmate Gardner (Pen. Code, § 187), and assault by a life prisoner that results in death (Pen. Code, § 4500). On appeal this court reversed petitioner’s conviction for the murder of Patch, but it affirmed his conviction and death sentence for the murder of Gardner. (See People v. Roberts, supra, 2 Cal.4th at p. 294.)
In a petition for habeas corpus filed in this court, petitioner asserted, as relevant here, that inmate witnesses Long, Cade, and Yacotis had lied at trial. This court appointed Superior Court Judge Franklin R. Taft as referee to determine whether the inmate witnesses had discussed their trial testimony among themselves. Specifically, the order directed the referee to ascertain what Long, Cade, and Yacotis saw of the stabbing and heard petitioner say about it, and whether their trial testimony against petitioner diverged from their perceptions. After hearing testimony recorded in almost 3,000 pages of transcript, the referee found that Long, Cade, and Yacotis each had testified falsely against petitioner at trial.
We are not bound by a referee’s findings on factual questions, but we accord them great weight if they are supported by substantial evidence. (In re Johnson (1998) 18 Cal.4th 447, 461 [75 Cal.Rptr.2d 878, 957 P.2d 299].) We defer to the referee’s factual findings, “especially those requiring resolution of testimonial conflicts and assessment of witnesses’ credibility” because the referee had “the opportunity to observe the witnesses’ demeanor and manner of testifying.” (Ibid.)
II. Testimony of Inmate Long
At petitioner’s capital trial, inmate Long testified that the day before the stabbing he heard petitioner threaten to kill fellow inmate Gardner. He also said that on the morning of the stabbing Long saw petitioner pull a prison-made knife from his clothes, stab Gardner, drop the knife, and run upstairs. In 1995 Long recanted his trial testimony, then in 1999 he retracted his recantation. The reference order directed the referee to determine whether Long heard petitioner discuss the stabbing beforehand, saw petitioner stab *749Gardner, and then saw petitioner run upstairs. At the reference hearing, Long invoked his Fifth Amendment privilege not to incriminate himself.
The referee found that before petitioner’s trial, while Long was housed at Chino prison with Leslie Rooks and David Calvin, these three prosecution witnesses were “overheard talking about the case, stating that they had to keep their [trial] testimony consistent.” The referee found that Rooks and Calvin “did in fact discuss the case” but, “with the exception of Long,” he did “not find any identifiable portion of their testimony to be fabricated.”
At the reference hearing, inmate Ruben Howard testified that while incarcerated at Chino he overheard one of the Long/Rooks/Calvin trio say petitioner did not stab the victim. Howard also heard Long say that petitioner had nothing to do with the stabbing. The referee noted that in Long’s 1995 recantation of his trial testimony against petitioner he specifically denied hearing petitioner discuss the stabbing of Gardner beforehand, seeing petitioner stab Gardner, or seeing petitioner flee up the stairs after the stabbing. Discounting Long’s 1999 retraction of that recantation, the referee found that during the interview with prosecutors that led to the retraction, Long was as concerned that petitioner might get off death row so he would pose a risk to Long as he was concerned about the truth or falsity of his conflicting declarations. The fact that Long had received “money and better prison housing” as well as a promise that the prosecutor would make “favorable recommendations” at Long’s parole hearing, coupled with Long’s conflicting 1995 and 1999 declarations, led the referee to conclude that Long’s trial testimony “should not be treated as believable.”
The majority refuses to credit this finding by the referee because at the reference hearing Long exercised his Fifth Amendment privilege not to incriminate himself and consequently did not testify at the reference hearing other than to disclaim much memory of the crime. Thus, the majority reasons, the referee had no opportunity to assess Long’s demeanor as a witness and hence Long’s credibility.
This court’s decisions have long applied the rule that “the offer of a witness, after trial, to retract his sworn testimony is to be viewed with suspicion.” (In re Weber (1974) 11 Cal.3d 703, 722 [114 Cal.Rptr. 429, 523 P.2d 229]; accord, In re Hall (1981) 30 Cal.3d 408, 418 [179 Cal.Rptr. 223, 637 P.2d 690] [“we routinely view recantations with suspicion”].) Although, as the majority points out, two Court of Appeal decisions have said that recantations are given “little credence” (maj. opn., ante, at pp. 742-743), this court has never adopted that standard. This court has never intimated that a recantation automatically is given “little credence.” (See maj. opn., ante, at *750p. 743.) Here the referee viewed with suspicion Long’s recantation of his trial testimony, but he found that Long had fabricated his trial testimony against petitioner. I would give that finding great weight because it is supported by ample credible evidence.
The majority dismisses Long’s 1995 recantation of his trial testimony against petitioner and his 1999 retraction of that 1995 recantation with the cursory comment that “it is clear that he has lied at some point.” (Maj. opn., ante, at p. 743.) One cannot assume that either of Long’s two versions was the truth. He may well have lied in both. What is clear is that Long is a liar. The referee found that because Long and the other inmates were “housed together” and because the investigators used leading and suggestive questions, “the inmate witnesses were able to learn the general theory of the prosecution’s case.” The prosecution’s theory was this: Petitioner, armed with a knife, waited outside the first floor clinic with codefendant Menefield. When fellow inmate Gardner approached, petitioner stabbed, while Menefield restrained, Gardner. In the next two to three minutes, petitioner ran upstairs to his third floor cell.
Although Long did not testify at the reference hearing, and the referee thus was unable to observe his demeanor and evaluate his credibility, the referee did observe three witnesses testify about Long. Inmate Howard, who was not a trial witness, testified at the reference hearing that at Chino prison he heard Long say petitioner had nothing to do with the stabbing of inmate Gardner.
Inmate Arthur Givens testified at trial that at Chino prison Long said he had not been present at the stabbing, and that he and other inmates were trying to align their trial testimony. At the reference hearing, Givens expanded upon his trial testimony: Long said he was reluctant to testify at petitioner’s trial, fearing the jury would discover they were lying, but Long planned to testify in order to get out of prison.
At trial inmate Yacotis testified that at Chino prison Long and Calvin were trying to tell consistent stories, but Yacotis denied overhearing lengthy coaching sessions between Long and Calvin, and denied saying he had overheard one of them say they were “lying for their freedom.” At the reference hearing, Yacotis testified that Long said he and the other testifying inmates would do “anything” to get out of prison and that Long, as the leader of the inmates who testified for the prosecution, was insistent they get their stories straight before trial.
Thus, although the referee had no opportunity to assess whether inmate Long’s reference hearing testimony was credible, the referee did have an *751opportunity to hear and assess the credibility of three other inmate witnesses who testified that before petitioner’s trial Long said he intended to testify falsely that petitioner had committed the stabbing, which Long acknowledged he had not seen. Moreover, the testimony of Yacotis and Givens at the reference hearing focused on Long’s motive to give false trial testimony, namely, Long’s stated belief that he would be released from prison in exchange for testifying against petitioner. Unlike the referee, neither the jury nor this court has had the opportunity to hear this testimony of these three witnesses.
Ample evidence presented at the reference hearing supports the referee’s finding that Long’s pretrial conduct and statements were at odds with his trial testimony. That evidence was bolstered by Long’s 1995 recantation of his trial testimony, which he retracted in 1999 when he feared petitioner might be released from death row. (See People v. Smallwood (1986) 42 Cal.3d 415, 431, fn. 10 [228 Cal.Rptr. 913, 722 P.2d 197] [retraction of recanted trial testimony “cast[s] some doubt on the credibility” of the witness].) Because the referee had an opportunity to assess the credibility of three witnesses to Long’s pretrial statements, and there is substantial evidence to support the referee’s finding that Long’s trial testimony against petitioner was false, I would adopt that finding.
III. Testimony of Inmate Cade
Inmate Cade testified at petitioner’s capital trial that he saw petitioner stab inmate Gardner, drop the knife, and run upstairs; shortly thereafter, while petitioner and Cade were both housed in a segregation unit, petitioner told Cade he had stabbed Gardner. This court’s reference order directed the referee to determine whether Cade’s trial testimony varied from what he had seen or heard at the Vacaville facility. Although Cade’s testimony at the reference hearing was consistent with his trial testimony, at the reference hearing the defense presented evidence that severely undercut Cade’s credibility as a witness. Newly disclosed documents and expert testimony about Cade’s institutional and psychiatric history came into evidence at the reference hearing.
Dr. Douglas Tucker, a forensic psychiatrist, testified that inmate Cade had a history of significant mental illness with several prior hospitalizations and in 1977 was found incompetent to stand trial. In February 1980, when Cade arrived at the Vacaville Medical Facility, medical records described him as psychotic, suffering hallucinations, and having inflicted injury on himself. By Cade’s account he stopped taking his antipsychotic medication about a week before the stabbing. In Dr. Tucker’s view, Cade’s ability to perceive, *752recall, remember, and relate events on August 17, 1980, the date of inmate Gardner’s stabbing, was probably somewhat impaired by the week without the medication Cade took to control aural or visual delusions. Dr. Tucker found various entries in the series of newly disclosed documents suggesting Cade was untruthful or unreliable, but Dr. Tucker offered no opinion on whether Cade had given truthful or untruthful trial testimony. As the referee notes, Dr. Tucker concluded “that Cade’s story was adjustable depending on what was to his advantage.”
Dr. Tucker further testified that although inmate Cade had a fairly severe mental illness, in conversation Cade would appear normal and could describe events he had seen. The referee specifically asked Dr. Tucker, assuming that Cade was delusional or hallucinatory, “Could a delusional event be created by the suggestion of someone else, such as a person interviewing Cade who feeds him some of the facts during questioning?” Tucker agreed that the effect of such suggestions could be to “modify and adjust [Cade’s] memory or perceived memory of what occurred.”
Deputy Attorney General Charles Kirk, the prosecutor at petitioner’s capital trial, testified at the reference hearing that Cade did not exhibit signs of mental illness at trial, that Kirk had seen the notation “insane” on Cade’s rap sheet, but that Cade had good recall of the stabbing. Members of the prosecution team testified at the reference hearing that in questioning Cade they had disclosed details of the stabbing, such as the number and location of Gardner’s wounds.
In light of the evidence summarized above, the referee concluded that although “Cade’s general account of the stabbing itself remained consistent” with his trial testimony, his testimony at the reference hearing was “evasive and often at variance with prior testimony.” The referee found Cade’s trial testimony “not truthful.”
Seizing on the referee’s isolated finding that Cade’s reference hearing description of the stabbing was “consistent” with his trial testimony, the majority considers “irrelevant” the referee’s answer to our question whether Cade’s testimony varied from what he actually saw or heard at the Vacaville facility in connection with inmate Gardner’s stabbing. (Maj. opn., ante, at p. 744.) The majority points out that at the reference hearing Cade did not give new evidence beyond what the jury heard at trial, and therefore this court should defer to the jury’s assessment of Cade’s credibility.1
The majority misses the point. True there was no new evidence from Cade. Instead, there was evidence that Cade may have been delusional at the *753time of Gardner’s stabbing, that he was anxious to tailor his story to suit the investigators, and that he was especially susceptible to having his perception of events altered by details of the crime learned from others. The jury at petitioner’s capital trial, however, never heard testimony about Cade’s mental health. The referee, who did, was in a better position to evaluate Cade’s credibility.
In my view, there is substantial evidence to support the referee’s finding that inmate Cade falsely testified at petitioner’s capital trial that he saw petitioner stab inmate Gardner. I would adopt the referee’s finding.
IV. Testimony of Inmate Yacotis
Inmate Richard Yacotis testified at petitioner’s capital trial that after the fatal stabbing of inmate Gardner, while housed in a segregation unit, he overheard a conversation between petitioner and codefendant Menefield. Petitioner asked Menefield why he had not picked up “the knife.” Menefield replied, “Because I was running right behind you up the stairs.” In 1995, Yacotis recanted that trial testimony, claiming that he had testified for the prosecution because he feared for his safety.
At the reference hearing in 2000, Yacotis stood by his recantation. He testified that he was originally going to testify for petitioner at trial, but switched sides when the prosecution told him that he “could be put on the [main] line as easily as [he could] be taken off.” Fearing retaliation by other inmates were he in the general prison population, Yacotis testified for the prosecution, feigning illiteracy in an effort to explain inconsistencies between his trial testimony and an earlier statement that bore his signature but had been prepared by another inmate.
At the reference hearing, Yacotis acknowledged being housed in the segregation unit two cells away from petitioner, but said he had lied about overhearing a conversation between petitioner and Menefield about the stabbing of inmate Gardner. He added that petitioner and Menefield were not housed close to one another in the segregation unit. Seeking to undercut Yacotis’s account, the majority points to prison records showing that after the stabbing, petitioner and Menefield had been housed in the segregation unit near one another for three days. Yacotis, however, consistently testified *754at trial and at the reference hearing that in the segregation unit he and petitioner were housed on one tier, and Menefield on another.
Although the referee recognized that recantations should be viewed with suspicion (In re Weber, supra, 11 Cal.3d at p. 722), the referee found Yacotis to be “sincere” and his reference hearing testimony “believable,” in part because Yacotis, who was out of prison at the time of the reference hearing, believed that were he ever to return “his recantation of his trial testimony would cause [him] difficulty with the authorities.” The majority acknowledges that the referee’s finding is entitled to great deference. It nonetheless concludes that the finding “even if believed” would not warrant habeas corpus relief. (Maj. opn., ante, at p. 743.)
Unlike the majority, I am persuaded not only that Yacotis gave false testimony against petitioner at the latter’s capital trial, but that the testimony was damning evidence of petitioner’s guilt. The conversation between petitioner and codefendant Menefield that Yacotis claimed to have overheard was, in effect, a confession by petitioner that he had stabbed Gardner and then fled, dropping the knife for Menefield to pick up. Moreover, it was an especially dramatic confession because it conformed exactly to the prosecution’s theory of the stabbing of Gardner.
V. Eyewitnesses to Stabbing
Of the five inmates who testified against petitioner at his capital trial as eyewitnesses to the stabbing of inmate Gardner, three identified petitioner as the stabber—Raybon Long, Ryland Cade, and Robert Hayes. Hayes was apparently deceased at the time of the reference hearing. The referee found no evidence that the trial testimony of Hayes was false.
False evidence is that which “is substantially material or probative on the issue of guilt” (Pen. Code, § 1473, subd. (b)(1)); it is evidence so significant that “ ‘with reasonable probability it could have affected the outcome . . . .’ [Citation.]” (In re Sassounian, supra, 9 Cal.4th at p. 546.) A reasonable probability is “such as undermines the reviewing court’s confidence in the outcome.” (Ibid.; In re Malone (1996) 12 Cal.4th 935, 965 [50 Cal.Rptr.2d 281, 911 P.2d 468].) The reasonable probability standard is an objective one, measured in light of all the relevant circumstances. (Ibid.) Here, the trial testimony of witnesses Long, Cade, and Yacotis was substantially material and with a reasonable probability could have affected the outcome of petitioner’s capital trial. Long and Cade both testified they saw petitioner stab Gardner. Without their testimony, the trial evidence identifying petitioner as the stabber is greatly weakened. According to inmate witnesses David Calvin and Norman Goodwin, it was Menefield who had stabbed Gardner.
*755At the reference hearing, the referee found that “Calvin generally reiterated his trial testimony.” Calvin testified that he saw two men involved in the attack on Gardner, but that the stabber was Menefield; although Calvin knew petitioner, the second man whose face he saw from 12 feet away was not petitioner. The referee found that no evidence had been presented to suggest Calvin’s trial testimony varied from what he saw during the stabbing.
Goodwin had testified at trial that he saw two men attack Gardner. One of the assailants was Menefield who stabbed Gardner three times, then ran up the stairs, followed closely by a second man whom Goodwin could not identify. Goodwin’s testimony was not included in our reference order.
Without the trial testimony of Long and Cade, there was only the testimony of Hayes that petitioner stabbed Gardner. By contrast, two witnesses, David Calvin and Norman Goodwin, testified that it was not petitioner but Menefield who was the stabber. Neither Calvin nor Goodwin identified the man accompanying Menefield; Calvin was certain that Menefield’s companion was not petitioner, whom Calvin had seen go upstairs before the stabbing, which occurred on the ground floor. Although there was testimony at trial that petitioner had threatened Gardner and was seen with a prison-made knife on the morning of the stabbing, it is reasonably probable that the jury would not have found petitioner guilty of assault and murder of Gardner without the false testimony of either Long or Cade, or both, that they saw petitioner stab Gardner, an account at odds with the testimony of eyewitnesses Calvin and Goodwin that it was Menefield, not petitioner, who had stabbed Gardner.
Accepting the findings of the referee, as I do, it is reasonably probable that the jury, faced with conflicting evidence of who had stabbed inmate Gardner in the hallway melee, would not have convicted petitioner of Gardner’s murder but for the false testimony from two fellow inmates that petitioner had confessed to stabbing Gardner. Accordingly, I would grant petitioner habeas corpus relief. (Pen. Code, § 1473, subd. (b)(1).)
George, C. L, concurred.
The majority notes that on appeal this court indicated that Cade’s trial testimony was thoroughly impeached. (Maj. opn., ante, at p. 744.) Cade was impeached with his reluctance *753to identify either petitioner or Menefield or other inmates who witnessed the stabbing, and with inconsistencies between his preliminary hearing testimony and his trial testimony as to which inmates were present. Because the jury did not hear any impeachment of Cade’s ability to perceive and recount the events of the crime, only of his willingness to name names, its assessment of Cade’s credibility as a witness was made without any evidence of Cade’s mental problems or his suggestability, and the impact of those problems on his credibility.