SINGAPORE - A detailed inspection of the perimeter fence at the Bishan depot, where an SMRT train was discovered vandalised, found no sign of any breach of entry.
This has raised the possibility that the act was an inside job, sources familiar with the investigation told The Straits Times yesterday.
The train was apparently spray-painted with graffiti between 1am and 5am on Monday, while it was parked - the third such incident in four years at an SMRT train depot.
The graffiti was spotted by staff monitoring CCTV cameras as the affected train was leaving the depot, said a source. It was then halted and withdrawn at around 5.30am, before it entered service.
SMRT had installed the CCTV cameras after the second incident, in August 2011.
Then, a vandalised train left the same depot in Bishan and had to be pulled back after a train officer saw that it had graffiti scrawled on its side.
In the latest incident, a red scrawl with traces of white, measuring 3m long and 1m high, was found on a middle carriage of the train.
A source told The Straits Times that it was "quite elaborate but looked incomplete".
It was, however, not signed off - as is the norm for graffiti artists - and no wording could be made out from the paint job.
The Straits Times understands that the train has since been scrubbed clean.
CCTV footage had confirmed that the vandalised train did not carry any signs of vandalism when it ended its run the night before.