A £500 reward has been offered for the return of jewellery stolen from a house in Oxhey which was left empty for 24 hours after a shock sink-hole appeared in the property.
Police believe the thieves forced entry to the Kingsfield Road property and climbed through the sink-hold to retrieve a number of valuable items, including a ruby eternity ring, a sapphire eternity ring and a silver spoon.
In addition, a safe, driving licence and documents were also stolen in the incident between 6pm on Friday, February 7, and 12.05am on Saturday, February 8.
Investigating officers are keen to talk to the woman who called at the victim's house and handed back the driving licence on February 10 after finding the card in the Otterspool area of Bushey.
Detective Constable Vishal Khanna said: "This is a very unusual incident whereby offender(s) would have had to climb into the sinkhole to retrieve the safe, which was wedged in partially collapsed shelving hanging over the hole.
"The offender(s) would more than likely have had brick dust stains on their clothing or mud on their trainers.
"If you recall seeing someone in the area or are aware of someone that you know who may have come home with dirt such as this on their clothing on that day, please call police with information. It may be that those responsible have spoken about what they have done as it is unusual and would urge anyone who knows anything to call."
Items described as having "extreme sentimental value" were stolen, including a white gold mounted ruby trap cut eternity ring, a white gold mounted square cut sapphire eternity ring and a solid silver Georgian Christening spoon.
DC Khanna said: "The victim is extremely keen to get these specific items back and a reward of up to £500 is being offered for their safe return.
"If you have any information on their whereabouts, you were the woman who handed back the driving licence, or you have any information whatsoever which would assist the investigation please call."
Anyone with information should contact DC Khanna via the Herts police non-emergency number 101 quoting crime reference number C1/14/583.