A supermarket employee was bitten on the arm when he tried to stop thieves from leaving a store.
Police are investigating an assault and theft which took place at a Sainsbury's on Wednesday May 20.
Police say three men entered the supermarket in Apsley at around 4.50pm and took alcohol and printer cartridges from the shelves.
Hertfordshire Constabulary have been told the men made no attempt to pay for the items they had taken.
A male member of staff aged in his 40s attempted to stop them leaving the supermarket but as he did so, he was assaulted and bitten on the arm.
The three men were seen leaving the scene in a blue Vauxhall.
CCTV images have now been released by investigating officers.
PCSO William Liddell, from the Kings Langley and Hemel Hempstead south east safer neighbourhood team, said: "Thankfully the victim was not injured following the assault but he was understandably left shaken by what happened.
"We have made extensive enquiries and are now releasing these images of a man we believe has information that could assist our enquiries.
"If you recognise him, or if you have any more information you believe could help, please get in touch as soon as possible.”
Anyone who can help with this investigation can email PCSO Liddell at william.liddell@herts.pnn.police.uk, report information online at herts.police.uk/report, call 101 quoting reference 41/39434/20, or call Crimestoppers anonymously on 0800 555 111.
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