A police investigation is underway after the body of UK antiques dealer Adrian Greenwood, 42, was found with multiple stab wounds in his Oxford home.

Known as a rare book dealer, author, historian and antiquarian, Greenwood was last seen grocery shopping at a Sainsbury on Tuesday. His housekeeper discovered his body in a hallway two days later.

Over the weekend, a 26-year-old was arrested on suspicion of murder and he was then released without charge by the police. 

Greenwood died after suffering a "vicious and sustained attack," according to police. As of Sunday, a murder weapon has not been found.

"We know Mr Greenwood had a number of businesses so anyone that had dealt with him from a business point of view or anybody that had a personal relationship with him - we will treat all of that information sensitively," said Det Supt Chris Ward.

"I think the answers lay in his personal life and his business connections and that's why I'm appealing for people to come forward that knew him".

Online profiles describe Greenwood as a graduate of  University of Oxford who completed an MBA at Imperial College London. He began his career selling lost property from British Rail, moving on to antiques, rare books, classic cars, and contemporary art, including a work by Banksy.

His clients included the British Library in London and the Getty Museum in Los Angeles. He also was known for selling first editions of Harry Potter, with one set stolen from a display in Oxfordshire only to be later recovered by police.

Greenwood specialized in 19th-century British military history and recently had written two books: Victoria’s Scottish Lion: The Life of Colin Campbell, Lord Clyde and Through Spain with Wellington: The Letters of Lieutenant Peter Le Mesurier of the ‘Fighting Ninth’.