Ten homes were burgled over the weekend - and police are linking them.
Properties in Borehamwood, Elstree, and Radlett were targeted between Friday and Sunday - each burglary happened in the early hours of each day between 3am and 5am.
Police have issued two CCTV images of someone they believe can help with their enquiries.
Detective Sergeant Gemma Badat said: "The person in these images could have information that is useful to the investigation so if you recognise them or the clothing they are wearing please get in touch.
"I would like to reassure the public the local Safer Neighbourhood Team is aware of this and increased patrols have been, and will continue to be, carried out in the areas.
"We are also reminding the public of the importance of home security and remembering to lock all doors overnight when you go to bed."
If you can help with appeal, call 101, visit herts.police.uk/report or call Crimestoppers anonymously on 0800555111.
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