A Newport Beach child likely will be added to the list of a former Los Angeles teacher's alleged sexual abuse victims, the Orange County district attorney's office said Friday.

Robert Pimentel, a 57-year-old Newport Beach resident who taught in a Wilmington school, was arrested Wednesday on suspicion of sexually abusing 20 children and an adult in Los Angeles County following an investigation started in March.

In 2005, the Newport Beach Police Department submitted a case involving Pimentel to the Orange County D.A., Chief of Staff Susan Kang Schroeder said. There were four alleged child victims — one from Newport Beach and three from Long Beach.

Schroeder said her office sent the case back to NBPD for further investigation twice between 2005 and 2007.

Ultimately, though, "insufficient evidence, lack of corroboration, problems with the availability of witnesses and other evidentiary issues" led the OCDA not to file charges, she said.

But now that other victims have emerged, Schroeder said, "the [Los Angeles district attorney's office] has requested for their office to handle all of our charges as well as their charges."

Transferring such cases between counties is not unusual, she said, and increases judicial economy. Furthermore, Schroeder added, victims don't have to testify more than once.

She said as far as she's aware, the LADA is only planning to file charges related to the Newport Beach victim.

LADA spokeswoman Sandi Gibbons said the cases have not been charged, but it is not unusual to combine cases from Orange County to ease the prosecution of an individual accused of crimes in both counties.

Pimentel taught at George de la Torre Jr. Elementary School.

More details of his life outside the school district emerged Friday.

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AYSO Volunteer

Pimentel volunteered for almost seven years in the local youth soccer community before he was suspended in March, American Youth Soccer Organization officials confirmed.

That's when Pimentel told AYSO Region 97 that he was under investigation by the Los Angeles Unified School District, though he didn't say what for.

Pimentel had worked as a registered volunteer coach and referee in the region since August 2005, according to an AYSO statement. Region 97 is a Newport-Mesa area division of the Torrance-based organization.

Pimentel coached boys and had a child who played soccer in AYSO, said spokesman George Passantino.

Although neither the district nor law enforcement contacted AYSO at the time, Pimentel's volunteer privileges were suspended immediately after the league learned of the investigation, as is standard any time allegations arise, he said.

"AYSO takes this very, very seriously, and when any type of a concern of this sort comes up, it is addressed," Passantino said. "It's not casting judgment, but we're making sure those kids are safe. You've got 500,000 kids. That's a big responsibility, and we're proud of the reputation we have in that arena."

In the statement, the league also said it is "prepared to work closely" with law enforcement, should that become necessary.

All AYSO volunteers, Passantino said, are subject to background checks and must complete the organization's "Safe Haven" training program.

No players or parents have reported abuse by Pimentel to AYSO, but the league is encouraging players' parents to contact authorities if they have any relevant information.

Neighbors on a quiet street off Irvine Avenue near the Costa Mesa city line said they were shocked to hear about Pimentel's arrest.

On a gray afternoon, as rain dripped from the toys and lawn decorations sitting outside stucco houses, some described Pimentel as friendly and outgoing.

One neighbor who declined to give his name said he's known the family for more than 20 years and is skeptical of the charges.

He said that Pimentel was a touchy-feely sort, but not creepy, and is a good father.

Erin Mosher, 33, was also surprised about the allegations, she said, as her 4-year-old son darted around her legs.

"I could see nothing like that from him," she said. "He's good with the kids. We've known him for years."

Pimentel, she recalled, seemed to be heavily involved with youth sports and would often joke around with her son about playing tee-ball when he got old enough.

She said she's not worried — "It is what it is."

"It's kind of unbelievable," she said. "But until there's evidence and stuff, you never know."

— Los Angeles Times Staff Writer Richard Winton contributed to this report.

jill.cowan@latimes.com

Twitter: @jillcowan