The theft of two small bronzes belonging to an artist from the county has led to Northampton Museum and Art Gallery upgrading its security.
The sculptures were delivered to the museum on November 27 - and were set to form part of the Town and County Art Society exhibition - when they were stolen at lunchtime the same day.
A Northampton Borough Council spokeswoman told the Chronicle & Echo that the bronzes were approximately worth £500.
She said: “The items had just been delivered to the museum, where they were intended to form part of the exhibition of the Town and County Art Society.
"The two small bronzes belonged to a local artist and were intended for sale at the exhibition. Their value is around £500. We immediately reviewed the circumstances of the theft and our security procedures.”
Northamptonshire Police has released CCTV images of a man they think may have information about the incident.
A spokesman said: "The man gained access to a closed-off area of the museum on Guildhall Road in the town centre. He is believed to have placed items, including a bronze sculpture, into his rucksack.
"Officers are appealing to the man in the images pictured or anybody who knows him, to call police on 101," he added.
Alternatively, they can call the independent charity Crimestoppers anonymously on 0800 555 111.