CCTV images of two men have been released following a mobile phone theft at Watford Metropolitan Station.
British Transport Police said the theft happen outside the station, in Cassiobury Park Avenue, at around 7.20pm on Monday February 10.
The suspects are then thought to have left the area in a taxi.
The force released the images as part of Operation Magnum, which is targeting theft on the Tube.
Detective Inspector Jez Walley said: "Officers investigating each of these cases have carried out several lines of enquiry, including circulating the images on police intelligence systems.
"We are now calling on the public to help identify the people pictured in the CCTV, as we believe they have key information that could help the investigations.
"If you recognise any of these people pictured, or have any information which could assist us, then I urge you to get in touch."
Anyone who recognises either of the people pictured is asked to contact British Transport Police on Freefone 0800 40 50 40, or text 61016, quoting LUA/B7 of 13/03/14.