SMITHFIELD — Attorneys Susan Doyle and Christi Stem were neighbors and friends for years. Stem counseled Doyle about marital problems. She is the godmother to Doyle's children.

But now Doyle - the two-term top prosecutor in Johnston County - is accusing Stem of having an affair with her husband, Michael. She filed a criminal conversation lawsuit Tuesday seeking a jury trial and at least $20,000 in damages from Stem, a private practice attorney in Smithfield specializing in family law. The move comes less than a week before Doyle is set to become president of the N.C. Conference of District Attorneys, a state agency.

The salacious 16-page court filing details a number of alleged marital infidelities and messages Stem exchanged with both Doyles.

Stem could not be reached for comment at her home or law office Wednesday. Michael Doyle did not return calls about the lawsuit and Susan Doyle's attorney, Heather Hayes Williams of Dunn, declined to comment.

North Carolina is one of only a few states that allow jilted spouses to file criminal conversation actions or alienation of affection lawsuits. State courts take these lawsuits seriously, however, often awarding significant financial damages. In March, the wife of a Raleigh trucking company owner was awarded $30 million in an alienation of affection lawsuit, one of the largest in state history.

Damages are awarded "with incredible arbitrariness," said Maxine Eichner, a law professor at UNC-Chapel Hill. "For many lawyers, that's the scary part of these things."

In the lawsuit, Doyle said that Stem was her friend for 17 years. Doyle and her husband, who are now separated, lived on the same block in Clayton as Stem and her husband. Susan Doyle claims in her filing that she confided in Stem about her marital problems in 2008 and 2009.

Doyle claims Stem had sex with her husband on multiple occasions throughout 2010 and the affair caused her "mental anguish, humiliation, injury to physical and emotional health and the loss of assistance and financial support of her spouse" resulting in "substantial damages."

Divorce attorneys say it is rare for a public figure to file such a lawsuit, which is known in legal circles as a "heart balm" action.

"The opportunity to be humiliated in front of your peers is not something elected officials often seek," said Lee Rosen, a Raleigh divorce lawyer. "It's not something that's good for your career long term. It's something that you need to deal with personally and privately."

Doyle, a Republican first elected district attorney for Johnston, Harnett and Lee counties in 2006, contends in court documents that she discovered Stem and her husband together at her home in October and that Stem admitted to the affair. The discovery happened during Doyle's heated re-election campaign against Benson Democrat George Murphy.

The day before, the lawsuit alleges, Doyle's husband sent Stem an electronic message that said, "I love you even when I can't touch you."

The lawsuit also claims Stem gave the Doyles legal advice about separation and child custody and helped Susan Doyle hire a private investigator to follow her husband in 2009.

Rosen, the divorce attorney, has pushed for North Carolina to ban alienation and criminal conversation lawsuits.

"The filing of this claim has the impact of destroying whatever is left of the families involved," Rosen said, adding that it makes an amicable divorce settlement nearly impossible.

Such suits, Rosen said, "are the province of unhappy people who are unable to move on with their lives. In most family law disputes, what you need is for the family to move on."

No court date has been set for the lawsuit. The filing asks Stem to respond within 30 days to dozens of claims that she can confirm or deny.

colin.campbell@newsobserver.com or 919-836-5768