A man has been killed in a "suspicious" house fire.
Detectives have launched an investigation after the blaze caught hold of the house in Hemel Hempstead, Hertfordshire, just after midnight on Saturday.
The victim, believed to be in his 60s, was pronounced dead at the scene.
Detective Chief Inspector Mark Ross is leading the inquiry.
He said: "Whilst the investigation is still in its early stages, we are treating the man's death as suspicious at this time.
"We are providing specialist support to the victim's family at this distressing time.
"Although this incident occurred during the night, the property is in a residential area and there may have been people who may have seen or heard suspicious activity.
"I would appeal to anyone who believes they can assist the investigation, to contact us as soon as possible."
Scenes of crime officers are working alongside specialist fire investigators from Hertfordshire Fire and Rescue Service to determine the exact cause of the fire.
Anyone with information should contact the major crime unit via the non-emergency number 101.