A federal judge’s decision to overturn an eight-year-old conviction for the high-profile murder of a Manhattan doctor that occurred 29 years ago has presented Manhattan District Attorney Cyrus Vance, Jr. with a difficult choice.

The district attorney must now decide whether to release Darryl Whitley from prison or to retry him within 60 days for the murder of 31-year Dr. John Chase Wood, who was fatally shot during a mugging on his way back to work at Columbia Presbyterian Hospital on the evening of Nov. 2, 1981.

On Thursday, Southern District Judge Alvin K. Hellerstein granted Mr. Whitley’s petition for a writ of habeas corpus, finding that the trial court had made an error of constitutional dimension when it allowed the recanted testimony of the chief witness against Mr. Whitley to be read, without cross examination, to the jury that convicted him of the Wood murder in 2002.

Prosecutors declined to comment on Judge Hellerstein’s ruling in Whitley v. Ercole, 06 Civ. 10198. But a retrial would require the rehabilitation of an unreliable cooperating witness who was promised leniency on a long prison sentence, testified against Mr. Whitley at his first trial in 1998 that ended in a mistrial, and later claimed he could not remember a key statement he had made to the lead detective in the case and took the Fifth Amendment.

On the night of the murder, Dr. Wood was returning to his shift at the hospital after walking home to comfort his pregnant wife. He was accosted on Riverside Drive by two men demanding drugs and, when a scuffle broke out, one of the men fired a .22 caliber handgun twice, killing the doctor.

It was not until 1994 that Glenn Richardson, a jailhouse informant with a history of drug use, told detectives that the shooter was Patrick McDowell and his accomplice was Mr. Whitley, then a teenager.

The two men were tried separately and both trials ended in a hung jury. Mr. McDowell’s second trial ended with an acquittal.

At Mr. Whitley’s first trial, Mr. Richardson told the jury, “I think that he [Mr. Whitley] said that they was on Riverside Drive, and they was looking for somebody to rob, and the doctor came along and Raynard [McDowell] shot him.”

Before the second trial, Mr. Richardson, by then out of jail, met with a prosecutor and told him he was concerned about testifying against Mr. Whitley and his memory of what Mr. Whitley had, in fact, told him.

The prosecutor relayed this news to New York Supreme Court Justice Budd Goodman, who then assigned an attorney, Samuel Feldman, to represent Mr. Richardson at an ex parte pretrial hearing on Nov. 26, 2001. The purpose of the hearing was so the judge could quiz Mr. Richardson about a 1994 statement to a detective implicating Mr. Whitley.

Mr. Richardson was late and Justice Goodman was not happy about it. “I don’t take crap from anybody,” the judge told him. “Now, Mr. Richardson, do you remember on May 10th, 1994 that you made a statement?”

Mr. Richardson, referring to his drug use, answered “Yes, but I was not clear and conscious during that statement.”

When Mr. Richardson said he did not “totally” remember making the statement, Justice Goodman warned him that, if he went to trial and claimed “amnesia” he could be held in contempt and put behind bars.

But when Mr. Feldman and Mr. Richardson appeared for another pretrial hearing in 2002, this time before the trial judge, Acting Justice Laura E. Drager, Mr. Feldman raised the possibility that Mr. Richardson had been coerced by the detective into giving the statement.

Mr. Richardson was not claiming amnesia, Mr. Feldman said, and intended to take the Fifth Amendment.

Mr. Feldman also represented that Mr. Richardson “wasn’t sure” that Mr. Whitley ever stated “that he was present and participated in the robbery of the doctor.”

Justice Drager went on to rule Mr. Richardson was an unavailable witness, reasoning that Mr. Richardson had been cross-examined on the statement, and cross-examined as well on the pressure he felt from the detective to implicate Mr. Whitley.

Justice Drager found there was “overwhelming reason” to doubt the “genuineness” of Mr. Richardson’s recantation, which she credited to the fact he was no longer in jail and no longer operating under a cooperation agreement.

The retrial began on Jan. 23, 2002, with Assistant District Attorney Joel J. Seidemann telling jurors that it was the “neighborhood’s worst-kept secret” that Mr. Whitley had been involved in the murder and defense lawyer Michael Yucevicius responded that the only evidence against Mr. Whitley was the testimony of convicted criminals.

‘Weak’ Case, ‘Basic Unfairness’

Justice Drager allowed Mr. Richardson’s statement from the first trial to be read to the jury, and it was read back to the jury twice during deliberations. Mr. Whitley was convicted of second degree murder on Feb. 6, 2002.

At the second trial, Judge Hellerstein said, “the state’s case relied heavily on the testimony of four jailhouse informants, all of whom had extensive criminal histories and received substantial benefits for their testimony against Whitley.”

But it was Mr. Richardson’s evidence, he said, that was the most important, as Mr. Richardson was the only witness who testified, albeit through his testimony from the first trial, as to hearing incriminating statements from both Mr. Whitley and Mr. McDowell, and he claimed to have lent Mr. McDowell his.22 caliber revolver in the fall of 1981.

After his conviction, Justice Drager sentenced Mr. Whitley to serve a prison term of 22 years to life.

In his 40-page opinion issued Thursday, Judge Hellerstein said Justice Drager erred in failing to tell the jury that Mr. Richardson claimed to not remember what he testified to at the first trial.

The omission, he said, was a denial of Mr. Whitley’s rights to a fair trial and due process of law in a case where the state’s case was “weak” and “there was no physical evidence tying Whitley to the crime.”

Justice Drager’s determination that Mr. Richardson had recanted and the recantation was not credible, he said, “is afforded less deference than usual,” because “it was based on representations of an attorney, little opportunity to observe demeanor, and on a ‘paper record’ of Richardson’s prior testimony.”

While Justice Drager was correct to rule that Mr. Richardson was unavailable, he said, allowing the testimony to be read without reference to his recantation “created a basic unfairness in the mix of evidence before the jury and compromised the Confrontation Clause of the Sixth Amendment.”

Mr. Seidemann said he is reviewing Judge Hellerstein’s decision.

Barry R. Ostrager of Simpson Thacher & Bartlett, along with associates Juan Arteaga and Chantale Fiebig represented Mr. Whitley pro bono.

Mr. Ostrager, who said when asked that he bills $1,050 an hour, and his associates spent “hundreds and hundreds of hours” on the case in the last three years as Judge Hellerstein ruled Mr. Whitley, who had filed pro se, had not yet exhausted his remedies in state court.

The lawyers had to go before the Appellate Division, First Department, which rejected their claims, and they found no relief before the New York Court of Appeals.

The case then returned to the Southern District, where Judge Hellerstein heard oral arguments in February by Mr. Ostrager and Assistant District Attorney Dana Poole.

“I always believed in the case and I think the factual recital and the marshalling of the law in Judge Hellerstein’s opinion makes it abundantly clear that Darryl Whitley didn’t get a fair trial,” Mr. Ostrager said Friday. “It frankly always disturbed me that the prosecution in this case proceeded as it did. I felt it was an honor to effectively represent Mr. Whitley.”