In 1974 Summerlin worked under immunologist Robert A. Good at the Memorial Sloan-Kettering Cancer Center in New York City, conducting research in transplantation immunology. He claimed that he could transplant tissue from unrelated animals by keeping the tissue in culture for four to six weeks. He used white mice with patches of black fur which he had colored with a black permanent marker.
Summerlin later attributed his deceptive behavior to a combination of mental and physical exhaustion, a heavy clinical and experimental workload, and pressure to publicize positive results. Memorial Sloan-Kettering president Dr. Lewis Thomas said that Dr. Summerlin was suffering from a "serious emotional disturbance. After the incident, Summerlin reportedly moved to rural Louisiana to practice medicine.
As a result of the Summerlin incident, the term "painting the mice" has become a synonym for research fraud. Author Joseph Hixson wrote a book about the scandal entitled The Patchwork Mouse.