Detectives investigating the murder of underworld gangster John "Goldfinger" Palmer have arrested a 43-year-old man, police said on 6 August.
Palmer, 64, was shot at his home on Sandpit Lane in South Weald, Essex on 24 June.
Police initially thought he had died as a result of a cardiac arrest, but a post-mortem revealed he had been shot in the chest. Sources have said the murder bears all the hallmarks of a professional hit.
Essex Police confirmed a 43-year-old man from Rugby was arrested on 6 August on suspicion of conspiracy to commit murder.
He has now been bailed until 23 September pending further inquiries.
DCI Simon Werrett, who is leading the murder investigation, said: "This is a positive development but we are continuing to appeal for witnesses to any suspicious activity in the area.
"Sandpit Lane is a popular spot for joggers and dog-walkers and I am particularly keen to hear from anyone who was in the vicinity between 16:00 BST and 18:00 BST on Wednesday, June 24."
The man with the Midas touch
Palmer left school unable to write or read, but made his fortune in the gold and jewellery business, and was worth an estimated £300m according to a 2004 Underworld Rich List compiled for the BBC.
He earned the nickname "Goldfinger" after being a suspect in the 1983 Heathrow Brink's-Mat gold bullion robbery, which netted the robbers £26 million.
Palmer admitted melting down gold in his Somerset garden shed, but said he didn't know it came from the robbery and was cleared.
The notorious Brink's-Mat robbery is referred to as Fool's Gold by underworld figures, as more than 20 people linked to the heist have met mysterious, untimely and often gruesome ends.
After his death was announced, Palmer's family issued a statement saying: "We are still in shock and trying to come to terms with the enormity of John's death.
"To lose someone you care about and who is a key part of your family so suddenly is traumatic and completely overwhelming.
"If anyone knows anything about John's death which could help police please get in touch with them so we can find some answers."