A Wisconsin man is suing a retired fertility doctor, alleging the physician used his own sperm as a donor while telling patients it came from an anonymous medical student — a deception that went undetected for more than four decades.
Joseph Laedtke Heider and his mother, Mary Ellen Lukezich, filed the lawsuit in Milwaukee Circuit Court against Dr. Frederick Dettmann, alleging fraud, medical malpractice, and related claims stemming from fertility treatments conducted in the early 1980s.
Background
Lukezich was a patient at Dettmann's fertility clinic in the early 1980s when she sought donor insemination services to conceive. According to the lawsuit, Dettmann assured Lukezich that the sperm came from a "healthy young medical student" who wished to remain anonymous.
Heider, now in his 40s, lived his entire life believing that anonymous donor was his biological father. The truth emerged in 2024 when Heider submitted his DNA to Ancestry.com for testing. The results revealed Dettmann as his biological father — not the promised medical student.
"The anonymous medical student donor that my mother was promised as my biological father never existed," Heider said at a June press conference, according to statements reported by WISN. "Instead, the DNA led back to one person. Dr. Frederick Dettmann, the very doctor my mom trusted to help her have a child. Words cannot fully express what it feels like to learn that your entire identity is built on a lie."
The Lawsuit
Attorney Al Foeckler filed the lawsuit on behalf of Heider and Lukezich. The Wisconsin Health Care Liability Insurance Plan and ABC Insurance Co. are also listed as defendants in the civil action.
"These families come to fertility doctors at their most hopeful and their most helpless time," Foeckler told reporters. "Trusting completely in the physician who holds their dreams of parenthood in their hands. Dr. Frederick Dettmann preyed on that desperation. He exploited that trust."
Dettmann, now 91 years old, has retired from medical practice. In a statement provided to local media through his attorneys, he denied any wrongdoing.
"The events referenced are alleged to have occurred almost 50 years ago," the statement said. "Dr. Dettmann has no independent recollection of the individuals making these allegations and is unaware of any evidence supporting the claims being asserted."
Key Takeaways
- Joseph Laedtke Heider discovered in 2024 via Ancestry.com DNA testing that Dr. Frederick Dettmann was his biological father, not an anonymous medical student donor as his mother was told
- Lukezich received fertility treatments at Dettmann's clinic in Milwaukee in the early 1980s
- The lawsuit, filed in Milwaukee Circuit Court, alleges fraud, medical malpractice, and related claims against Dettmann, now 91
- Dr. Dettmann has denied any wrongdoing through his attorneys, stating he lacks recollection of the alleged events
- Heider learned the truth about his biological parentage more than four decades after his conception
What's Next
The case is pending in Milwaukee Circuit Court. The defendants have not yet filed a formal response to the allegations in court records. No criminal charges have been announced, and it remains unclear whether prosecutors will pursue any action given the passage of time since the alleged conduct occurred.
Court dates for substantive motions or trial have not been scheduled at this early stage of litigation.