The man arrested on suspicion of murdering Jo Yeates has been described by neighbours as an eccentric "pillar of society".
Chris Jefferies, 65, lives in a flat above the one he rented to Miss Yeates and her boyfriend.
Mr Jefferies is a retired public school teacher who taught English at Clifton College, just yards from his home in Canynge Road, in the Clifton area of Bristol.
Miss Yeates vanished after returning to the basement flat on 17 December.
Her body was found on a grass verge about three miles away on Longwood Lane in Failand on Christmas Day.
Mr Jefferies is understood to have told neighbours he thought he had seen Miss Yeates leave the flat with two others on the evening she disappeared.
But hours after the claim was revealed, he was arrested by police.
Neighbours have said that Mr Jefferies, a bachelor who sports a distinctive mane of straggly white hair, plays a prominent role in his local Neighbourhood Watch group.
He is also a member of a local historical group dedicated to conserving buildings in the area.
Ray Lowman, who lives opposite Mr Jefferies, said: "I knew him through the Neighbourhood Watch.
"I'm amazed by it really but also find it quite disconcerting."
Asked about Mr Jefferies' community activities, Mr Lowman said: "He is basically a pillar of society. One of the well-known familiar locals."
He acknowledged Mr Jefferies', at times, unconventional manner of dress.
"It is one of the problems. His appearance is unusual.
"We weren't good friends. I wouldn't say he was weird but unusual and the hair is an affectation.
"He's a very intelligent man, very sharp."
Mark Moore, headteacher at Clifton College, said Mr Jefferies had taken early retirement in 2001.
He had formerly been head of English at the independent school, which has fees of more than £9,000 a term.
There were no disciplinary issues recorded against the former member of staff, Mr Moore said.
"There was nothing in his record at all," he said. "He took early retirement, which he's perfectly entitled to do, when a new head of English came into the school and he decided to bow out."
Mr Moore said: "I've been headmaster here for six years and I've certainly never met Mr Jefferies and there will be very few people on the current teaching staff, and pupils, who have ever met Mr Jefferies.
"Although he lived locally, he had no formal contact with the college since he retired."
Mr Jefferies was vice chairman of his local Neighbourhood Watch, and an active member of Clifton and Hotwells Improvement Society(Chis) which campaigns to conserve buildings.
Chis secretary RoseMary Musgrave said: "He's certainly an active member and does come to meetings from time to time. He's not a member of the committee though."
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 and wrote a series of letters to Bristol City Council outlining the group's opposition to the scheme.