A convicted killer once sentenced to life with no possibility of parole received a new, shorter sentence Thursday because Orange County authorities improperly used a jailhouse informant to gain information.

The killer, a Santa Ana gang member, could be free as soon as 2019, based on a plea deal announced Thursday by the Orange County district attorney. Leonel Vega originally was convicted in 2010 of chasing down and shooting a rival gang member in the head.

Orange County Superior Court Judge Dan McNerney called the reduced sentence a “black eye” for county prosecutors and the Sheriff’s Department.

With the Vega plea, three Orange County murder cases have been reduced because local prosecutors or police investigators have misused jailhouse informants. Defense attorneys are looking into other cases.

Police and prosecutors took a pounding Thursday in two Santa Ana courtrooms as the backlash continued from an investigation by the Orange County Public Defender’s Office into the district attorney’s surreptitious use of jailhouse snitches to get confessions.

At issue is the fact that the district attorney and local police have admitted using paid jailhouse informants to record suspects in custody after those suspects have been formally charged, a violation of their constitutional rights.

The Vega deal came the same day as a judge in the case of admitted mass murderer Scott Dekraai interrogated an Orange County sheriff’s deputy about a computerized system for tracking jail informants and inmates. Defense attorneys say the system has been kept secret by the department for 20 years.

Vega, 34, received a 15-year sentence for the 2004 shooting of 17-year-old Giovani Onofre. Vega was serving a life sentence with no possibility of parole.

Judge McNerney noted the lack of candor and disclosure by the government in using jailhouse snitches, said defense attorney Todd Melnik.

Vega was given credit for nearly 8 1/2 years time served, Melnik said.

Susan Kang Schroeder, the district attorney’s chief of staff, said the plea deal was not a black eye. Instead, she said it is an example of how far the office will go to police itself. The department is retraining its prosecutors and the police departments on how to use informants and when to turn over information.

“The district attorney took a proactive step after they discovered the mistake and brought the defendant back without a request by the defense,” Schroeder said. “We tried to mitigate the damage that had been done.”

Schroeder admitted the deal was hard for the victim’s family to accept.

“I completely understand why people would be upset and the victim’s family would be upset. Mr. Vega did not receive the full punishment he would have gotten,” Schroeder said.

“But sometimes, when law enforcement makes mistakes, the tie goes to the defendant.”

In the Vega case, District Attorney Tony Rackauckas’ office said in a statement that a Santa Ana detective prompted a jailhouse informant to elicit information from Vega, without disclosing it to prosecutors. The informant testified at Vega’s trial, helping to secure a conviction. The detective who planned the use of the informant is now retired.

The informant was promised by police help in getting into the military. Letters, tapes and other evidence uncovered by defense attorney Sanders show that officials up to the rank of assistant sheriff knew of the effort to illegally use informants against Vega.

Vega, who shot his victim once in the head, isn’t the only killer to benefit from what prosecutors are calling “mistakes” in the use of informants and the lack of timely disclosure to defense attorneys.

In September, Isaac John Palacios admitted in court that he shot a rival gang member 15 times. With credit for time served, Palacios was released from jail within hours of his confession – because of problems with a jailhouse snitch.

Long a secret weapon, the use of snitches unraveled last year with an investigation by Assistant Public Defender Scott Sanders, who is representing Dekraai. Sanders contends that prosecutorial misconduct in the case is grounds to take the death penalty off the table. Dekraii has admitted shooting eight people at a Seal Beach salon in 2011.

In August, Judge Thomas Goethals, in the Dekraai case, concluded that prosecutors and police committed misconduct with informants, but that it was unintentional.

Sanders also is trying to get the entire Orange County District Attorney’s Office removed from the Dekraai case, as well as that of another homicide defendant, Daniel Wozniak.

In the Dekraai courtroom, Judge Goethals repeatedly questioned a deputy on the tracking of informants at the jail. Goethals was especially interested in why deputies in previous testimony had not told him of the computerized tracking system for informants and inmates, called “TRED.”

Deputy Zachary Bieker, testifying for the first time, said he had mistakenly thought that TRED records were “not allowed in court.”

Bieker also said selected deputies have access to the password-only system.

Bieker was one of three deputies who handled inmates at the jail. Goethals has called them to his courtroom to determine why deputies withheld the existence of the TRED system during previous hearings. At least two more deputies are expected to appear Monday before Goethals.

Contact the writer: tsaavedra@ocregister.com