Police want to talk to a man shown in video footage outside one of property developer Jeff McCloy's inner-city office buildings on the night it was tagged with graffiti.
The Newcastle Herald reported last month that Mr McCloy was offering a $1000 reward to help catch the person who wrote the initials DOS on a wall of the Telstra Building on the corner of Darby and Hunter streets.
The closed-circuit TV footage shows a man wearing a black cap, black face mask, black Nike jacket, grey jeans and white sneakers walking up and down a driveway behind the building.
He removes a black backpack from his shoulders as he walks towards the obscured rear corner of the building.
Police said the man in the video could be responsible for the graffiti or could help identify the offender.

Mr McCloy said the incident happened about 12.20am on Friday, October 16.
The former Newcastle lord mayor said he had tried unsuccessfully to clean the wall with a high-pressure hose and would be forced to render and paint it.
REPORTED EARLIER
Mr McCloy wants to "run the guy through the courts" to force him to pay for the repairs and as a warning to other would-be graffiti artists.
"I'll put a $1000 reward up for anyone who can nominate and identify this kid," he said.
"The reason to do that is to find him, have the police charge him and make him pay for the restoration, even if I have to run him through the courts.
"This has hardly been done before, but there's only one way to send a message to them that they're destroying other people's property."

Mr McCloy, whose office is in the Telstra building, believes the DOS tag has appeared elsewhere in Newcastle.
He has long railed against the "rampant" graffiti he says reflects "social decay" in inner-city suburbs.
"Thank goodness for some of those murals which have gone up now and covered a lot of the bad spots, but that won't stop them continuing to deface our city," he said.
"It lowers the tone of the city. No one cares about what the city looks like, the cleanliness, the tidiness."
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