The man, who police have not named, lives near to Mrs Buxton's house in the village of Marston on Dove. He was arrested yesterday and taken into custody for questioning, but has not been charged.
Police said that the murder inquiry was still active. They were also anxious to trace a man on a mountain bike who was seen several days earlier near where the attack took place.
Mrs Buxton, 35, was found lying on a footpath at a secluded beauty spot beside the river Dove, two miles from her home. She had set out to exercise her two Weimaraner gun dogs on Tuesday afternoon while her husband, Ronald, a restorer of antique books, returned from a business trip to France.
Her body was discovered by a passer-by. She was fully lothed and there was no evidence of a sexual attack. She had been stabbed 10 times through the chest and back.
Yesterday, Detective Superintendent Ron McAllister, the officer in charge of the investigation, said that the murder weapon, which had not been found, was a single-edge blade not less than six and a half inches long and one inch wide.