SANTA ANA (AP) — In an Orange County courtroom, attorneys have dueled for a year over allegations that authorities misused jailhouse informants, hid evidence and lied on the witness stand.

On Thursday, they are expected to make final arguments on whether convicted mass killer Scott Dekraai should have his life spared or the district attorney’s office recused from his case over the allegations.

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The case highlights challenges related to the use of jailhouse informants often known to be unreliable and long decried by defense attorneys. But the extensive hearing delving into the systematic use of snitches has been unprecedented, prompted other case reviews and could lead defense lawyers in Orange County to raise similar claims, legal experts said.

Last year, Dekraai’s lawyer Scott Sanders accused prosecutors of trying to cover up a jailhouse informant program that had trained snitches to sidle up to high-profile defendants to elicit information in violation of their constitutional rights.

After months of testimony, Judge Thomas M. Goethals barred prosecutors from using an informant’s testimony and found they failed to turn over crucial evidence about the snitch to Dekraai, but let the case proceed.

Dekraai, who killed his ex-wife and seven others in a shooting rampage in a Seal Beach hair salon, was headed toward a penalty phase when Sanders, an assistant public defender, uncovered new jail records detailing inmates’ movements that he believed could shed light on how authorities had used the snitch to chat up his client.

It also raised questions for him about why prosecutors had failed to turn over evidence related to Dekraai, and the honesty of sheriff’s deputies, who did not previously disclose the existence of the records during testimony about how inmates’ movements were tracked.

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The records prompted Sanders to renew arguments that his client can’t get a fair trial from county prosecutors.

“The willingness to endorse the brazenly false testimony of witnesses because it is perceived as helping to secure a penalty phase trial demonstrates a conflict,” he wrote in a brief filed ahead of Thursday’s hearing.

While prosecutors concede the hearing has cast an unflattering light on the use of jailhouse informants, they said the newly-uncovered records didn’t reveal anything new about why Dekraai and the snitch had been housed in adjacent cells.

In addition, since the informant’s testimony isn’t being used, “any taint has been decisively cut out,” senior deputy district attorney Howard Gundy wrote in a brief.

Lt. Jeff Hallock, a spokesman for the Orange County Sheriff’s Department, declined to comment on the proceedings while they are under way.

Matt Cherry, executive director of Death Penalty Focus, said it’s too soon to know whether the hearing will have an effect beyond the county, but the discovery of decades of jail records might prompt defense attorneys in Orange County to seek a review of old cases involving snitches.

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“It’s not just the ongoing cases where it may be raised,” said Cherry, whose group opposes the death penalty. “We need to look at past cases and find out if there’s people who are now in jail, who may not be in jail if the prosecutors had acted legally in their cases and not withheld information.”

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