A 32-year-old man suspected of murdering Joanna Yeates was being questioned by detectives for a third day today.
The suspect was detained in the early hours of Thursday after police investigating the 25-year-old landscape architect's death uncovered fresh evidence.
Soon afterwards, specialist search teams moved into a neighbouring flat in the building where Jo lived at 44 Canynge Road, Clifton, Bristol.
Dutch engineer Vincent Tabak, 32, is registered as living at the address with his girlfriend, Tanja Morson.
Workers have erected scaffolding and a 12ft high green tarpaulin at the rear of the substantial converted Victorian property where Miss Yeates and Mr Tabak lived.
The screen covers the entrance to Flat 1, where Mr Tabak lived, and the rear of Jo's rented home that she shared with her boyfriend, Greg Reardon, 27.
Forensic examinations were continuing yesterday in Canynge Road and at a converted terrace property about a mile away in Aberdeen Road, Cotham, where it is believed Mr Tabak was arrested in the early hours of Thursday.
Police officers have also been seen at the offices of Mr Tabak's employer, international consultancy Buro Happold, in Lower Bristol Road, Bath.
The firm, and several colleagues, referred all inquiries to Avon and Somerset Police.
Mr Tabak, a trilingual engineer, is an expert in the flow of people through buildings, including sports venues.
Eindhoven University of Technology confirmed he completed a PhD in ``User Simulation of Space Utilisation'' three or four years ago.
Neither Mr Tabak nor Miss Morson, an analyst at Dyson, in Malmesbury, Wiltshire, could be reached by telephone.
It is thought the Dutchman had just returned to Britain from a holiday, having reportedly spent Christmas in Holland with his family.
Acquaintances described him as an intelligent and industrious young man.
Former university colleague Jeroen Harink said: ``He was generally regarded by everyone as being very smart and very hard-working.
``I think he was a nice guy but he didn't socialise much. You'd never see him out in bars or clubs.''
Another former colleague, Louisa Wickham, 27, who worked with Mr Tabak for a year, described him as quiet but a ``very cheerful and friendly guy''.
She added: ``He was well thought of at Buro Happold. He was always being sent to other offices to help out.
``It was clear from the start he was very clever and very good at his job.''
Mr Tabak's arrest was the Jo's frozen body was found dumped in a lane on the outskirts of Bristol on Christmas Day.
Mr Reardon reported her missing after he returned to Bristol on December 19 following a weekend away visiting family in Sheffield.
A huge police operation swung into action after her body was found on the verge in Longwood Lane, Failand, North Somerset.
Police have said there was no evidence that she had been sexually assaulted but they have not ruled out a sexual motive.
It is understood they are investigating whether Jo's body was taken from her home in a large bag or suitcase.
The line of inquiry arose because there were no drag marks on her body or clothing.
It has also been claimed that police found three separate foreign DNA traces on different parts of her body.
Her landlord, Chris Jefferies, 66, was arrested on December 30 and questioned for three days on suspicion of murder before being released on bail.
Avon and Somerset Police, who have refused to name the man in custody.
Jo's father welcomed the latest development, which comes almost five weeks after his daughter disappeared.
Speaking at the family home in Ampfield, David Yeates, 63, said he was ``pleased'' the police investigation was ``moving forward''.
He said: ``We know as much as you do. We were told at 6am this morning that someone was arrested on suspicion of Jo's murder and their age.''