Chris Jefferies, a 65-year-old bachelor, taught English at Clifton College, just yards from his flat, from the early 1970s before taking early retirement in 2001. He was chairman of the Bath and Avon Prayer Book Society as well as an enthusiastic activist for the Liberal Democrats in Clifton and an active member of the Neighbourhood Watch and Clifton and Hotwells Improvement Society, which campaigns to conserve buildings in the area.
He owns three flats in the block where he lives and is also believed to own several properties across Bristol and in France.
He is said to have a keen interest in Christina Rossetti, a 19th century poet who often wrote about death.
Mr Jefferies was arrested yesterday at his flat directly above the basement Victorian property he rented to the 25-year-old landscape architect and her boyfriend Greg Reardon, 27.
Forensic officers spent yesterday conducting an inch by inch search of both Miss Yeates' flat and Mr Jefferies' property.
Two cars - a silver Chrysler Neon and a grey Volvo S40 that was on Jefferies' drive - were removed for examination.
Neighbours have described Mr Jefferies, who sports a distinctive mane of straggly white hair, as a "nutty professor-type".
Resident Tony Buss, 51, said his arrest yesterday came as "a shock and surprise".
Another neighbour, a 26-year-old man who did not want to be named, said: "We see him all the time on the road. He's a bit of a nutty professor-type by the looks of it."
In 2005, he was at the forefront of efforts to stop building work on fields near his home.
He led the Canynge Road Campaign Group to save the fields from development.
Ray Lowman, who lives in a flat opposite the mansion where Mr Jefferies and Miss Yeates lived, said: "I'm amazed by it really but also find it quite disconcerting. He is basically a pillar of society, one of the well-known familiar locals."
Mr Lowman acknowledged Mr Jefferies' at times unconventional manner of dress.
"It is one of the problems. His appearance is unusual," he said.
"I wouldn't say he was weird but unusual. A very intelligent man, very sharp."
Clifton College head Mark Moore said Mr Jefferies had at one time been the school's head of English and said there were no disciplinary issues recorded against him.
Miss Yeates was last seen on December 17 and her snow-covered body was found on Christmas morning. She had been strangled.
An Avon and Somerset Police spokesman confirmed a 65-year-old man was arrested at an address in Canynge Road at 7am yesterday and had been taken into custody at a police station within the force area for questioning.
It was reported today that police investigating Jo Yeates' death are to look at links to an unsolved murder committed near her home in 1974. Glennis Carruthers, 20, was found strangled outside Bristol Zoo. At the time police interviewed 16,000 people but no one was charged.