A 71-year-old Wisconsin woman and her 43-year-old son have filed a lawsuit against a retired fertility doctor, claiming a DNA test revealed he secretly used his own sperm during a 1982 artificial insemination, a betrayal of trust that went undetected for decades.
Mary Ellen Lukezich sought help from Dr. Frederick Dettmann more than 40 years ago after medication and surgical treatments failed to help her conceive. Dettmann, then a practicing OB-GYN, recommended artificial insemination and told Lukezich the donor would be an anonymous "healthy young medical school student," according to the lawsuit filed August 6 by attorney Al Foeckler. Instead, the complaint alleges, Dettmann used his own sperm, and Lukezich gave birth to her son, Joseph Laedtke Heider, the following year.
The deception stayed buried until December 2024, when Heider submitted his DNA to Ancestry.com. What came back upended his life.
Heider told NBC News he received an email from Ancestry.com notifying him of a half-sister match. When he dug into the results, the picture grew worse:
"I got an email from Ancestry, which is the company that I ordered the DNA test from, that I had a half sister. And so when I went into the DNA results and the relationships, I had noticed that there was multiple half siblings that it had suggested that I was related to."
By tracing those genetic connections, Heider identified a direct link to Dettmann's family. The lawsuit alleges that Dettmann is Heider's biological father, and that Heider has nine other half-siblings fathered by the doctor. If that allegation holds, it would mean Dettmann carried out this kind of substitution far beyond a single patient.
Heider spoke publicly at a news conference in June, months before the lawsuit was filed. His words were plain.
"Words cannot fully express what it feels like to learn that your entire identity is built on a lie."
Lukezich, now 71, described the discovery in starker terms. She told reporters: "I feel like I've been raped. And it's not right. And I want other women to feel OK about coming forward with this."
Dr. Frederick Dettmann, now 91 and living in Arizona, has denied wrongdoing. His legal team issued a statement saying the events "are alleged to have occurred almost 50 years ago" and that Dettmann "has no independent recollection of the individuals making these allegations and is unaware of any evidence supporting the claims being asserted."
That denial sits alongside a separate statement attributed to an individual identified in reporting only as "Gaynor", whose full name, title, and relationship to Dettmann are unclear, who said Dettmann was "never sued, disciplined, investigated, had his licensure challenged, nor were any ethical complaints ever made against him."
But the record is not quite that clean. Cases like this one, where DNA evidence surfaces years after the fact, often expose gaps in institutional oversight that allowed misconduct to go unchecked.
Three years after Lukezich's insemination procedure, Whitefish Bay police received an accusation that Dettmann had assaulted a woman during a gynecological exam, as TMJ 4 reported based on police records. No charges were filed. Police cited that proving the assault would be "too difficult."
The complaint was forwarded to Wisconsin's medical licensing board, which closed the case in 1986 after what the board described as a consideration of the facts and a vote. Dettmann retired in the 1990s.
Today, both sets of records are gone. Whitefish Bay Police Chief Patrick Whitaker told NBC that all records about the 1985 case would have been destroyed under record retention laws that applied at the time. A spokesperson for the Wisconsin Department of Safety and Professional Services told NBC the agency does not have records of closed complaints from that long ago.
So the paper trail that might have corroborated, or contradicted, the current allegations no longer exists. The institutions that were supposed to hold Dettmann accountable in the 1980s produced no lasting record of their work. That is not evidence of innocence. It is evidence that the system discarded its own receipts.
Attorney Al Foeckler said that after the June press conference, multiple women contacted him with accounts of uncomfortable interactions with Dettmann dating as far back as the 1970s. Foeckler did not specify how many women reached out or whether their accounts have led to additional legal claims.
Foeckler's characterization of Dettmann was blunt. At the news conference announcing the lawsuit, he said families seeking fertility treatment come to their doctors "at their most hopeful and their most helpless time," trusting the physician completely. He accused Dettmann of exploiting that trust.
"There is no question in my mind that this man was a serial predator of women."
That is the plaintiffs' attorney's characterization, not a proven finding. But the allegation that a doctor secretly fathered a patient's child, combined with the claim of nine other half-siblings and accounts from additional women spanning decades, paints a picture of conduct that, if true, represents a profound abuse of medical authority.
Heider himself framed his decision to sue in personal terms, saying he wanted to hold Dettmann accountable "for the pain that he caused my mom and the things he put her through, that maybe she didn't even know at the time." The deception Heider describes, one that shaped his entire identity, is not the kind of thing that can be waved away with a claim of faulty memory. Stories of elaborate personal fraud, like that of a Rhode Island con man who faked his own death and lived under a false identity, remind us how far some individuals will go to conceal the truth.
The August 6 complaint names Dettmann as the primary defendant, along with the Wisconsin Health Care Liability Insurance Plan and ABC Insurance Co. The specific court, case number, and damages sought were not detailed in available reporting. The Daily Mail reported reaching out to the insurance defendants, Lukezich, Heider, and Dettmann for comment.
Several critical questions remain unanswered. How was the figure of nine half-siblings determined? Are the women who contacted Foeckler pursuing separate legal action? And what specific relief are Lukezich and Heider seeking from a 91-year-old retired doctor whose alleged misconduct predates most modern fertility-fraud statutes?
Fertility-fraud cases have surfaced across the country in recent years as consumer DNA testing has made it possible for donor-conceived individuals to trace their biological origins. The pattern is consistent: a doctor in a position of absolute trust substitutes his own genetic material, and the truth stays hidden until technology catches up. The patients never consented. The children never knew. And the institutions that licensed and oversaw these physicians often destroyed the records that might have exposed them sooner.
When the people charged with safeguarding trust destroy the evidence and shrug at the timeline, accountability doesn't disappear, it just takes 40 years and a $99 DNA kit to arrive.