A 34-year-old woman has been arrested on suspicion of murder after a man died falling under a London Tube train.
British Transport Police were called to King's Cross station on Monday evening to reports a man was under a Piccadilly Line train.
The woman, from the Cricklewood area of north London, was arrested at the scene and remains in police custody.
Police said early indications from witnesses were that the victim and the suspect knew each other.
Murder detectives are working to identify the man, thought to be middle-aged, and trace his next-of-kin.
Det Supt Ashley Croft said: "Early indications from witnesses are that the victim and the suspect knew each other.
"We are also in the process of viewing CCTV from the station and interviewing several witnesses who came forward last night.
"It's really important that we build the clearest possible picture of what took place on the platform and I ask anyone who may have seen the incident to contact us."