A swastika was daubed in a police station in north London in an area only police officers and staff can access.
The graffiti was discovered by police in Edmonton Police Station in February and deemed a "faith-based hate crime" - but a lack of forensic leads meant the case was closed without identifying a suspect.
In a statement, a Metropolitan Police spokesperson said: "On 15 February 2019 graffiti was found on the wall in the lift lobby area of Edmonton Police Station. The graffiti, in biro, was a swastika symbol.
"The incident was recorded as a faith hate crime and a senior investigating officer at Detective Chief Inspector level was appointed to investigate the offence.