Stanley M. Gartler , a molecular biologist and geneticist who helped provide the first convincing evidence that cancerous tumors develop from a single mutated cell involving the first collection of human cells to permanently thrive in a laboratory, died on May 25 at his home in Seattle. He was 102.

In 1965, while studying genetic markers that vary in human cells, he found that in 18 supposedly independent cultures, the genetic markers were identical. It became clear to him that the supposedly unique cells had become contaminated by the first permanent human cell line called the HeLa line, an abbreviation of the first and last names of Henrietta Lacks, a Black woman who had died of cervical cancer in 1951. Her genetic information harvested from a tissue biopsy shortly before her death had been shipped and studied in laboratories around the world without her consent or her family’s knowledge.

Dr. Gartler’s discovery has been credited as a catalyst for improved quality control in labs and enhanced authentication of cell lines. The story of the HeLa line became one of the defining lessons of 20th-century medicine, and raised important ethical questions about informed consent of patients, privacy and the rights of families to receive compensation for research on a relative’s cells.