Four people have been arrested on suspicion of murdering a farmer who has been missing for more than three months.
William Taylor was last seen at his farmhouse in Gosmore, near Hitchin, Hertfordshire, on 3 June.
Three men, aged 18, 22 and 53, and a 52-year-old woman, all from Hitchin, have been arrested.
They are being held on suspicion of murder, conspiracy to murder, arson and conspiracy to commit arson.
Hertfordshire Police said Mr Taylor's body has not been found.
Specially trained officers carried out an "extensive search" of land within a 1.7km (1.05 mile) radius of Mr Taylor's farm after he went missing.
The farmer was last seen wearing a pale blue shirt, jeans and black wellies, and may have been wearing a navy-blue boiler suit.
A friend who was staying with Mr Taylor reported him missing on 4 June after waking up to find he was gone.
Mr Taylor's 70th birthday has passed since he disappeared.