Walkers who could have information about the murder of a Lincolnshire businessman are being sought by police.
David Twigg, 46, was found dead on 13 March after being locked inside a cupboard in a building in Station Yard, Burgh Le Marsh, which was set on fire.
Officers want to speak to people who may have been in the vicinity of the workshop on 12 or 13 March.
A public footpath runs close by the property and walkers have been known to cross land owned by Mr Twigg.
Police said they would like to speak to a man and a woman who may have been walking in this area on the Saturday or two men who were challenged about their route on the Sunday morning.
Mr Twigg and his partner Julie Dixon were attacked at the workshop he owned in the former railway goods depot.
Ms Dixon escaped but Mr Twigg, who is thought to have died from breathing in smoke, was found later.
Det Ch Insp Stuart Gibbon, of Lincolnshire Police, said: "Detailed forensic analysis of the building has taken place since 13 March and I can confirm that David Twigg was locked inside a cupboard within the workshop during the fire.
"There was no key in the lock when the emergency services forced the cupboard door to reach Mr Twigg."