A murder investigation is under way after historian Adrian Greenwood was found stabbed to death following a "vicious and sustained attack".
Police were called to Iffley Road in Oxford at around 3pm on Thursday after the 42-year-old was found by his cleaner in the hallway of his four storey house.
He was pronounced dead at the scene and a post-mortem examination gave the cause of death as multiple stab wounds.
Thames Valley Police are yet to recover the murder weapon, which they believe is a bladed article.
Formal identification is yet to take place but detectives are satisfied the man was Mr Greenwood, who was also a biographer, author and art dealer.
A 26-year-old man who was arrested on suspicion of murder was released without charge on Saturday.
The head of the Thames Valley Police major crime unit, Detective Superintendent Chris Ward, said: "We believe that Mr Greenwood was an historian, biographer, author and a dealer in art, cars and other historic artefacts.
"He was usually smartly dressed, and often wore a tweed jacket."
He continued: "We believe that an altercation has taken place in the hallway of this house. The post-mortem confirmed that Mr Greenwood died following a vicious and sustained attack.
"It is very likely that the offender may have injuries as a result of this altercation."
Detectives are keeping an open mind in terms of motive, and would like to speak to anyone who may have information to come forward.
Mr Ward added: "The investigation team would like to hear from anyone who has information about Mr Greenwood's associates, or anyone who has had a personal or business engagement with him in the last few weeks.
"The last sighting of Mr Greenwood was at Sainsbury's supermarket in Oxford Road, Kidlington, at about 6pm on Tuesday 5th April.
"If you saw him after this time we would also like to hear from you."
Mr Greenwood was educated at the £35,000-a-year Tonbridge School in Kent, where he was taught by Sir Anthony Seldon, the historian and biographer of John Major, Tony Blair and Gordon Brown, according to his personal website adriangreenwoodbooks.co.uk.
A graduate of politics, philosophy and economics from Christchurch College, Oxford, he followed in his former history teacher's footsteps by becoming an historian and biographer in his own right.
The Oxford alumnus penned two historical biographies and also traded rare and antiquarian books, including texts which he provided to the British Library and Getty Museum, according to his website.
The BBC also reported that Greenwood was responsible for the sale of a piece by the graffiti artist Banksy, worth £60,000, in April 2011.
His website also says that his first book, Victoria's Scottish Lion, a biography of British Army officer Sir John Campbell, was nominated for the Templar Medal Book Prize.
His most recent text, Through Spain With Wellington, was launched in March, less than a month before his death, and is available to buy on Amazon.
A special collector of Harry Potter books, Mr Greenwood gained national media attention in November 2010 when one of his first edition novels, worth £6,000, was stolen from an exhibition gallery in Woodstock, Oxfordshire.
According to the Oxford Mail, the thief attempted to return the book in a carrier bag following the public interest in the story, but was caught by police and later jailed for six weeks.