A Santa Ana man’s conviction for murder and his life sentence in prison were vacated Monday in Orange County Superior Court — in the first case overturned following disclosures from an unprecedented hearing on prosecutorial conduct.

Judge Gregg L. Prickett approved the elimination of Leonel Santiago Vega’s 2010 conviction for the 2004 gang-related murder of Giovanni Onofre after negotiations between prosecutors and Vega’s attorney.

Todd L. Melnik, Vega’s appellate attorney, said his client’s constitutional rights to counsel were violated when the Orange County District Attorney’s Office and Sheriff’s Department improperly used jailhouse informants to secure damaging admissions and failed to properly turn over details about the informants to Vega’s defense attorney.

The questionable use by prosecutors of a network of informants in county jails to obtain information from defendants has been the centerpiece of an explosive evidentiary hearing in the case of Scott Evans Dekraai, who last month pleaded guilty to the 2011 slaughter of eight people, including his ex-wife, in a Seal Beach hair salon.

Vega’s conviction was cited by Dekraai’s public defenders as one of the more outrageous examples in what they claim is a wide pattern of cases where defendants had their rights to counsel and due process violated through the use of informants.

Scott Sanders, Dekraai’s lead public defender, is seeking to have the death penalty for Dekraai blocked and the DA prosecutors recused from the case because of their use of informants in his case and associated rights violations.

Regardless of how Superior Court Judge Thomas M. Goethals rules on Sanders’ motion in the Dekraai case, the Vega ruling demonstrates the potential impact of its revelations.

Early this year, the Vega family had hired Melnik — a Woodland Hills attorney who specializes in habeas corpus writs — to ask the federal courts to overturn his conviction.

Then when it was disclosed during the three-month Dekraai hearing that Vega’s prosecutor, Erik S. Petersen, hadn’t fully disclosed notes, reports and tapes by informants during his trial, Melnik, one of many defense lawyers watching the case, seized on the new information to open negotiations with the DA’s office

Those talks led to the stipulation by prosecutors yesterday to vacate Vega’s conviction and sentence, with the acknowledgement more informant material should have been discovered to the defendant.

Marc Rozenberg, a top assistant district attorney who appeared in Prickett’s court after negotiating the deal, declined comment.

In the murder trial, prosecutors alleged Vega — now 34, but a member of the Delhi Gang since he was 15 years old — shot Onofre, of the Alley Boys Gang, in a car after an altercation at a park.

Melnik said there is little evidence to support that theory, save what came from the informants.

Prior to the Dekraai hearing, Vega was in Corcoran State Prison, but was moved earlier this month to jail here.

Monday, he was in a group holding cell in Prickett’s court when his conviction was vacated. Asked how his client felt, Melnik said: “He was all smiles.”

Several members of Vega’s family also were in court, expressing joy and elation after the court’s decision. But they declined comment.

As part of the stipulation Monday, Vega will not be released on bail. A hearing will be held Sept. 12 on the next steps in the case.

Melnik and prosecutors are in negotiations on whether he is retried, or a plea deal is reached.

To gain the conviction, court records show prosecutors engaged three informants to testify against Vega. One was Oscar Moriel.

At the Dekraai hearing, Moriel said it was his “job” for years to be a jailhouse informant in multiple cases, as prosecutors haven’t pursued felony charges against him.

Moriel acknowledged during extensive questioning by Sanders that he hoped to win a shorter sentence for his eager prosecutorial assistance.

Another informant was Johnny Belcher — who had a history of four prison terms, and then was facing multiple new felony drug charges with penalty enhancements, records show.

When Petersen was questioned at the Dekraai hearing by Sanders, attorneys say, the prosecutor didn’t recall Belcher receiving any break after his testimony.

But Melnik noted Petersen later acknowledged, after being confronted with documents, that Belcher was allowed to plead to lesser charges and avoid jail after his testimony in the Vega case.

Vega’s Santa Ana attorney, Rob Harley, “asked all the right questions” when his client was on trial on the murder charge, Melnik said; but the prosecution didn’t disclose the evidence, as required by multiple precedential court cases.

“Wow, holy cow,” said Harley, when he learned from a reporter that Vega’s conviction was dropped. “I was screaming, pitching my usual hissy fit during the case. But all my little cries of non-disclosure went unanswered by the judge.”

Harley said that during the trial he recalled Vega’s judge, William R. Froeberg, saying he “was sure” the prosecutor knows his discovery and disclosure obligations and follows the laws.

“This shows the prosecutor did not know his obligations, or ignored them,” Harley said.

Rex Dalton is a San Diego-based journalist who has worked for the San Diego Union-Tribune and the journal Nature. You can reach him directly at rexdalton@aol.com.

Join the conversation: In lieu of comments, we encourage readers to engage with us across a variety of mediums. Join our Facebook discussion. Message us via our website or staff page. Send us a secure tip. Share your thoughts in a community opinion piece.