The Metropolitan Police has said it is concerned for the welfare of one of its constables, who has been missing for six days.
Gordon Semple was last seen on Great Guildford Street in central London as he made his way to work in Westminster at 3pm on 1 April - and the force has released a CCTV image of that sighting.
This newly released image shows the last-known sighting of Mr Semple
The serving officer was reported missing by his partner after he failed to return home that evening, and Scotland Yard is now treating the investigation as a high-risk missing person's inquiry.
The Homicide and Major Crime Command is leading efforts to find Mr Semple.
The serving officer was reported missing by his partner
Detective Chief Inspector Cliff Lyons, who is running the investigation, said: "We continue to retain an open mind concerning the circumstances of Gordon's disappearance, and consideration has been given to whether he may have become a victim of a crime.
"However, at this stage this is just one line of enquiry - it is still hoped he will return home safe and well."
Police are keeping an "open mind" about his disappearance
Investigators have determined Mr Semple had left The Shard at lunchtime on the day of his disappearance - but they do not know where he was between 12.30pm and 3pm, the time of his last sighting.
Mr Semple, who was last seen wearing brown shoes, dark trousers and a lilac shirt, is 5ft 10ins tall, white, of a large build and has a shaved head.
The investigation is being treated as a high-risk missing person's inquiry
DCI Lyons has said he is keen to hear from anyone who has spoken with Mr Semple since Friday, adding: "I would like to reassure anyone concerned about calling the police, that they will be treated with the utmost sensitivity and strictest confidence."