A man whose body was found on railway tracks was chased before he died, police have said.
The remains were spotted by a train driver close to Knockholt station, near Sevenoaks, Kent, just after midnight on Monday.
Officers believe the victim is a 24-year-old from Croydon, British Transport Police said.
His death was initially treated as non-suspicious but a murder inquiry has since been launched.
British Transport Police has released CCTV footage of a man with dark hair, wearing dark clothing, that they would like to speak to in connection with the incident.
Police said they believe the victim was chased into the station and on to the tracks by another man shortly before 21:30 GMT on Sunday.
A short while later, the other man walked back on to the platform and left the station, they added.
Police said a post-mortem examination was due to take place.