Spray cans have been found near where three men died after being struck by a train.
Police were called to Loughborough Junction station in south London, an area known for graffiti.
It's reported that paint was found nearby and the three people may have been killed overnight, when freight trains run.
Officers were seen taking photographs of graffiti. The victims are believed to have been in their 20s.
Officers have told the family of one man and are working to identify the next of kin of the other two.
The first call to police was made by a train driver but the force is still trying to identify the train that hit the men.
There have been no reports of any passenger services being involved, which suggests they were struck by a freight train.
Loughborough Junction is managed by Thameslink and located on a line between Herne Hill and Elephant and Castle stations.
Anyone with information can contact police by texting 61016 or by calling 0800 40 50 40.