LEWISTON – Dr. Merrill S.F. Greene, a family doctor who served for more than 60 years as a medical examiner for Androscoggin County, died Tuesday at the age of 102.

The Harvard-educated doctor probably served longer as a medical examiner than anyone in the country, said Dr. Henry Ryan, Maine’s former chief medical examiner.

While maintaining a private practice in Lewiston, Greene started serving as a part-time medical examiner in the 1930s, decades before the state developed an organized system for determining how someone had died.

He was known to many as “Alphabet,” a nod to his initials M.S.F., for Merrill Shelden Fredrick. His demeanor was professional, commanding and a bit crusty.

“He was a salty old character,” Ryan said. “And he was there for you.”

Even into his 80s, Greene answered emergency calls in the middle of the night, driving through snowstorms or walking along country trails to get to the scene of a death.

“I’m a doctor,” he once told Ryan. “When people call, I expect they need me.”

A native of Athens, in western Maine, Greene was graduated from Colby College and Harvard Medical School. He married his college sweetheart, Harriet Sweetzer, who worked with him as his assistant for most of his career.

The work as a medical examiner was an add-on, a low-paid bit of public service. But he was driven by duty, according to people who knew him.

“He went way out of his way for folks,” said Capt. Ray Lafrance of the Androscoggin County Sheriff’s Department. “When we called, he was always there.”

During World War II, he joined a group of Maine doctors who formed the 67th General Hospital, which worked to prepare England to treat wounded GIs.

By the 1980s, his health had begun to fail him, but he kept on helping police. A friend often would drive him to the scene of a fatal car crash or shooting.

“You name it. He’d go anywhere,” Lafrance said.

Greene taught police about wounds and would explain how injuries happened. “When he left, everyone understood what he thought had transpired,” Lafrance said.

He never gave up being a doctor, no matter his age.

Even when he moved into Montello Manor nursing home in 2000, his shingle continued to hang outside his home.