The machine allows forensic processes that would normally be carried out in the lab to be done at the scene.
There was a sign outside the building saying 'Do not enter, dangerous chemicals'.
Officers wearing white suits came out wearing masks while a number of uniformed officers entered Mr Jefferies' flat on the opposite side of the building.
Police earlier hinted that they believe Miss Yeates's killer may have had an accomplice.
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Joanna Yeates's landlord had been watched before arrest
Detectives had been watching Joanna Yeates's landlord for several days before arresting him on suspicion of her murder, it emerged tonight.
Police arrested Chris Jefferies, 65, who lives in the building where Yeates had a flat, after reports that he had seen the Bristol landscape architect on the night she vanished were carried in the media.
But detectives had been keeping a close eye on retired public school teacher Jefferies even before his claims surfaced in public, sources with knowledge of the investigation said.
As police began to question Jefferies a picture of an eccentric but respected member of the community emerged.
Jefferies taught English at the nearby fee-paying Clifton College. He was an active member of the local Liberal Democrats and knew the leader of Bristol city council, Barbara Janke.
He was familiar to police as a leading light of the Neighbourhood Watch scheme and for a while was chairman of a society promoting the continued use of the 1662 Book of Common Prayer.
White-haired Jefferies, who is unmarried, hit the headlines yesterday when neighbours claimed he had told police he saw 25-year-old Yeates leaving her flat on the night she vanished with two other people. When approached by journalists outside his flat, Jefferies appeared to row back from the claims, saying what he had said to police was vaguer than how it had been reported.
"I definitely cannot say that I saw Joanna Yeates that evening. No," he said.
He added: "Everything I am aware of I have told the police and I don't really want to talk about it."
Shortly after 7am today an unmarked police car pulled up outside Jefferies's flat in the affluent Clifton area of Bristol and he was arrested.
A spokesman for Avon and Somerset police said: "Just after 7am this morning, police attended an address in Canynge Road and arrested a 65-year-old man on suspicion of murder. He has been taken into custody at a police station and detained for questioning. …
"Detectives investigating Joanna's murder are continuing to carry out forensic examinations and are also continuing to appeal for anyone with any information that can help the inquiry to call the Operation Braid incident room."
Police took away two cars – a silver Chrysler Neon parked on the street and a grey Volvo S40 that was on Jefferies's drive. Forensic searches of his flat were being carried out and bags of items were carried out. Uniformed officers carried out house-to-house inquiries in the neighbourhood.
Yeates's family said they were pleased that there appeared to be progress. Her father, David, an IT worker from Ampfield in Hampshire, said: "At this time our focus is still with Jo. We are pleased the police have made an arrest as they have been working very hard to make progress in this case. During the investigation police have not told us everything they have discovered but we understand there are certain things they cannot reveal."
Jefferies, who in his younger days sported blue hair, taught English at the fee-paying Clifton College and former pupils said he was particularly fond of the Pre-Raphaelites. One student called him a "stickler for discipline and very traditional". The college headteacher, Mark Moore, said there were no disciplinary issues recorded against Jefferies. Other pupils have said he was an inspiring, if unconventional, teacher.
In an article in a college magazine, former student Stuart Delves called Jefferies and his colleagues in the English department "paramours of literature". Jefferies, Delves wrote, "pronounced interesting places in interesting ways and illuminated Christina Rossetti for us."
Jefferies retired nine years ago and threw himself into other interests. He became a Lib Dem activist, vice-chairman of his local Neighbourhood Watch, and an active member of Clifton and Hotwells Improvement Society, which campaigns to conserve buildings of historic interest.
Neighbour Ray Lowman, who knew Jefferies through Neighbourhood Watch, said: "He is a pillar of society – one of the well-known familiar locals. A very intelligent man, very sharp."
Yeates was last seen on Friday 17 December at 8.40pm when she bought a pizza from a supermarket close to her home. She was reported missing two days later and her body was found on a roadside verge three miles away on Christmas morning. She had been strangled.