IOWA CITY, Iowa — A former University of Iowa researcher has pleaded not guilty to killing his wife in 1997.

John Richard Bloomfield entered the plea in writing Thursday. The filing waived his right to an in-person arraignment hearing, which had been scheduled for today.

Authorities arrested Bloomfield in November at his home in St. Paul.

Minn. after conducting additional DNA testing in the unsolved murder of 57-year-old Frances Bloomfield, whose body was found in a ditch outside Rockford, Ill., in September 1997.

Bloomfield was extradited to Iowa to face a first-degree murder charge. Investigators believe she was strangled at the couple’s Iowa City home.

Bloomfield’s attorney, Leon Spies, said Thursday that he would soon ask for a review of his client’s $1 million bond. He says Bloomfield’s “health is precarious.”