Police say their investigation continues into the murder of Michael Griffiths, whose body was found following a fire at his home in Fernhurst in January.
Officers are speaking to members of the antique trade locally who were acquainted with Mr Griffiths or may have had business dealings with him.
Det Ch Insp Jeff Riley said: "We have identified that Michael had a keen interest in militaria and attended a number of fairs at Bisley.
"I would appeal to anyone who knew him or has any information about his business activities, either through the antiques trade or the militaria meeting, who have not spoken to us, to get in touch.
"We have not ruled out any potential motive for Michael's murder.
"We have not identified the two youths or men who called at his home earlier in the week and snowballed the house when he answered.
"We do know that when they called they claimed to be police officers, so at this stage, we are still connecting them with the enquiry.
"We are very keen to establish who they were and if anyone else had the same experience or saw them in the area on the Tuesday night (January 22) before the fire.
"Similarly, we have not yet traced the black SUV or 4x4 that was seen in the area on the morning of the fire and as a result, this remains a suspicious vehicle of interest to us.
"The crime scene was severely damaged by the fire and as a result the associated forensic work was exhaustive and complicated. We have established that accelerants were used to start the fire.
"I am determined that those responsible for Michael's death will be brought to justice. If you have any information, no matter how small, that could assist us with our enquiry, please contact Sussex Police on 101 quoting Operation Killick."