A judge on Thursday dismissed the murder case against a 73-year-old doctor who had been ordered to stand trial in the 1968 death of his first wife.

Ingham County Chief Circuit Court Judge William Collette said the passage of time hindered both the prosecution's case as well as Charles William Mercer's right to a fair trial. He was charged last year in Sally Sue Mercer's death.

"I cannot fathom how you can proceed with a case that is 39 years old without some reference back to the initial investigation and gathering of evidence that occurred," Collette said.

In January, Ingham County District Court Judge Rosemarie Aquilina had ordered Mercer to stand trial, sending the case to circuit court despite reservations about evidence that she called inconsistent and unreliable.

"Bill is obviously relieved," defense lawyer Chris Bergstrom told the Lansing State Journal. "We thought all along this would happen."

A message seeking comment on the ruling was left Thursday by The Associated Press with the Ingham County prosecutor's office.

Prosecutors had argued that the Okemos surgeon was the only person who could have killed his wife. But much of the evidence in the case, including original police reports, blood and tissue samples and witness interviews either was lost or destroyed.

Sally Mercer, 31, died Feb. 27, 1968, at the couple's Okemos home.

Doctors originally listed the cause of death as polio. But the case was reopened in the 1990s. In 2003, an autopsy showed her body tissue contained high levels of a pain-reliever called propoxyphene.