Some four decades after his wife died, a 72-year-old physician has been charged with her murder.

Charles William Mercer, who works at Ingham Regional Medical Center, was arrested in his home Monday and charged with open murder in the case of his wife's death 38 years ago, which had been thought to be caused by polio.

Chris Bergstrom, an attorney for Charles Mercer, declined comment.

Sally Sue Mercer died Feb. 27, 1968, at the couple's Okemos home. At the time, a pathologist ruled she died from bulbar polio.

Ingham County Sheriff Gene Wriggelsworth told the Lansing State Journal that improvements in forensic science and "old-fashioned detective work" led to the doctor's arrest. Investigators interviewed witnesses across the country, he said.

Wriggelsworth declined to say what the actual cause of death was or what information led to Mercer's arrest. He said there are no other suspects.

The sheriff said authorities long suspected foul play and reopened the case in 1995. In 2001, Sally Mercer's death certificate was changed to say she was the victim of a homicide. A second autopsy in August 2003 showed the death was not caused by polio.