MASON, Mich. (AP) -- A lawyer for a Lansing-area doctor who is accused of murdering his wife 38 years ago may conduct recorded interviews with witnesses to preserve their testimony, a judge says. Judge Rosemarie Aquilina issued the ruling as a preliminary examination continued in 55th District Court. The judge will decide whether Dr. Charles W. Mercer should stand trial on an open murder charge in the Feb. 27, 1968, death of his wife, Sally S. Mercer. The death originally was blamed on bulbar polio. Investigators now say she died from an overdose of a painkiller and that her body showed signs of a struggle. The 72-year-old Okemos doctor was arrested June 5. He is free on a $1 million bond. Defense lawyer Chris Bergstrom said Tuesday that witnesses will help show that Sally Mercer died from a viral infection.