Cash and jewellery were stolen when a home in Letchworth was burgled last week.
The burglary took place in Haymoor sometime between 8am on Friday and 1.15pm on Saturday.
It is believed that the suspect entered over a fence at the rear garden and forced entry through a patio door.
Cash and jewellery were taken from the property, including two gold pocket watches and a gold signet ring which holds sentimental value.
PC Nicole Goodyer, who is investigating, said: "Our enquiries are continuing, and I am appealing for anyone with information to please get in touch.
"If you saw anyone acting suspiciously in the area around this time, please get in touch. Additionally, if you have a doorbell cam fitted, please check it, as you may have recorded some crucial footage to assist our investigation. You can email me at nicole.goodyer@herts.police.uk with any information, no matter how small or insignificant you think it may be."
You can report information online at orlo.uk/moLOV, speak to an operator in the Force Communications Room via the online web chat at orlo.uk/mxg95 or call the non-emergency number 101, quoting crime reference 41/5648/24.
Alternatively, you can stay anonymous by contacting the independent charity Crimestoppers on 0800 555 111 or via their untraceable online form at crimestoppers-uk.org.
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