DNA Test Links Couple, Dead Baby : Lawsuit: County had contended that the parents switched a healthy infant with one that died of birth defect. Lawyers now agree to seek a settlement.

A DNA test performed on tissue from a baby who died nearly 17 months ago from an undiagnosed birth defect forced Los Angeles County to back down late Tuesday from its contention in a medical malpractice suit that the baby was switched.

Although the test could not definitively prove that Patty Chavez was the mother of Steven Ruiz, it showed that she and her boyfriend, Reynaldo Ruiz, could have been the baby’s parents.

Assistant County Counsel Robert Ambrose said the results provided the “conclusive proof” that the county sought to support the contention that the couple were the baby’s parents. He said the matter will go before a judge who will help the parties reach a settlement.

“There’s been enough on this,” Ambrose said. “We would like to see if we can conclude it.”

After being told of the test results by her attorney, Chavez said, “I was jumping up and down. . . . I just started crying for all the happiness that I had.”

“It’s been really hard, with people blaming me and all. . . . But I just knew they were going to say that the baby was mine, because it was.”

Although the couple’s attorney, Aileen Norvell Goldstein, had sued the county for $250,000, the maximum award for medical malpractice, she said Tuesday night that she thought Chavez and her family deserve more.

“I’m ecstatic for this girl and for her family that this thing is behind them . . . and they are not forced to exhume their baby and that . . . the county has completely conceded that they are wrong,” she said.

Chavez and Ruiz, who live in Northridge, have charged that nurses and doctors at the county’s Olive View Medical Center in Sylmar failed to diagnose a congenital condition that left the baby with no anal opening.

Attorneys for the county had maintained in court papers that Steven Ruiz was not the baby born to Chavez five days earlier at the hospital.

After the case became public earlier this month, the county acknowledged that it had not thoroughly investigated its claims that the baby who died at Northridge Hospital Medical Center was not the same one born at Olive View. The county had maintained that minor discrepancies in medical records at Olive View and at the county coroner’s office showed that there were two babies.

Blood samples and gum scrapings from Chavez, 17, and Ruiz, 21, were tested Tuesday by a USC pathologist and were compared with tests on the baby’s tissue sample.

The test, known as PCR, or polymerase chain reaction, uses heat and bacteria found in natural thermal pools to amplify the DNA patterns that can provide clues to a person’s identity from a sample as small as a hair follicle.

But the tissue in this case had been stored in a formaldehyde solution by the county coroner’s office and scientists and attorneys disputed whether a PCR test performed on such a sample could be reliable.

Ambrose had said earlier in the day that the county would accept the results of the test performed by a USC pathologist regardless of whether it bolstered the county’s case.

The county ordered that the PCR test be performed on the preserved tissue sample last week after Goldstein threatened to have the baby’s remains exhumed from San Fernando Mission Cemetery and tested to prove that her clients were the parents.

Traditional DNA testing methods are widely used in court cases because they can provide a certain match, similar to a fingerprint, between a specimen taken from a crime and blood or tissue from an accused criminal.