Adrian Greenwood: New arrest over Oxford art dealer death
A second man has been arrested on suspicion of murdering an antique dealer.
The body of Adrian Greenwood, 42, was found by his cleaner in the hallway of his four-storey house in Iffley Road, Oxford, on Thursday.
He had been repeatedly stabbed in the chest and neck in what police called "a vicious and sustained attack".
Thames Valley Police said a 50-year-old man from Peterborough was arrested on Sunday.
A 26-year-old man was arrested on Thursday on suspicion of murder but has now been released without charge.
The last sighting of Mr Greenwood was at Sainsbury's supermarket in Oxford Road, Kidlington, at about 18:00 BST on Tuesday.
Police are appealing for people who knew him to come forward to enable detectives to build up a picture of his life and associates. The murder weapon has not been found.
Detective Chief Inspector Kev Brown said: "It's crucial that anyone with any information about Mr Greenwood's background or the murder comes forward as soon as possible.
"I would like to thank all those members of the public who have already come forward with information. A number of lines of enquiry are being pursued."
Mr Greenwood was an Oxford graduate who had written two historical biographies and traded rare and antiquarian books as well as art.
In 2011, he spoke to the BBC ahead of an auction of Banksy artworks in Oxford, where he sold a locked 1970s safe stencilled by the artist.
Mr Greenwood was also in the news in 2010 when his limited first edition of a Harry Potter book was stolen from an art gallery in Woodstock.
It was later found in a carrier bag outside a shop in Abingdon.