Detectives are questioning the landlord of Joanna Yeates on suspicion of her murder.
Retired public school teacher Chris Jefferies, 65, was arrested at 7am on Thursday at his flat directly above the basement Victorian property he rented to the 25-year-old landscape architect and her boyfriend Greg Reardon, 27.
The bachelor's arrest came just 24 hours after he claimed he had watched as three people left Miss Yeates's flat in Canynge Road, in the upmarket area of Clifton, Bristol, on the night she vanished.
Neighbours have described Mr Jefferies, who sports a distinctive mane of straggly white hair, as a "nutty professor-type" who was active in his community - playing a prominent role in his local Neighbourhood Watch group.
He taught English at Clifton College, just yards from his flat, from the early 1970s before taking early retirement in 2001.
Mr Jefferies, a enthusiastic activist for the Liberal Democrats in Clifton, is also a member of the Clifton and Hotwells Improvement Society (CHIS), which campaigns to conserve buildings in the area.
Police took away two cars - a silver Chrysler Neon parked on the street and a grey Volvo S40 that was on Mr Jefferies's drive - for examination.
Forensic officers spent Thursday in both Miss Yeates's flat and Mr Jefferies's property - taking away large brown evidence bags from both.
Miss Yeates was last seen on December 17 and her snow-covered body was found on Christmas morning by a couple walking their dogs in Longwood Lane in Failand, North Somerset. She had been strangled.
Her parents, David, 63, and Theresa, 58, said they were pleased an arrest had been made.
