These images show the last known sighting of Westminster police officer Gordon Semple, who has been missing since last Friday (April 1).
Police released the CCTV stills on Wednesday (April 6) as concern continued to grow for the 59-year-old's safety, with one line of enquiry that he may have been a victim of crime.
The footage shows Mr Semple last Friday (April 1) at 3pm in Great Guildford Street, Southwark, which runs between Southwark Street and Union Street.
He left home that day to attend work as a police constable in Westminster and was reported missing by his partner after failing to return that evening.
Police said they have established he left the Shard at around 12.30pm that day, and they are trying to establish his movements between then and 3pm.
'Calls will be treated with strictest confidence'
Detective Chief Inspector Cliff Lyons, who is leading 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 that he will return home safe and well...
"We are yet to identify if Gordon met with anyone in that area, or was merely passing through. He can be seen looking at his mobile telephone, but not making or receiving a call.
"I am very keen to hear from anyone who spoke with Gordon at any point since Friday, 1 April, or anyone with information which could assist our enquiries and establish his current whereabouts.
"I would like to reassure anyone concerned about calling the police, that they will be treated with the utmost sensitivity and strictest confidence."
The investigation is still being treated as a high-risk missing person inquiry, but due to concerns for Mr Semple's welfare the Homicide and Major Crime Command is now leading the efforts to find him.
Mr Semple is described as a white man, 5ft10ins, with a large build and a shaven head. He was last seen wearing brown shoes, dark trousers and a lilac shirt.
Anyone with information is asked to call police on 020 8721 4961, or Crimestoppers, anonymously, on 0800 555 111.
