A pensioner was tied up and robbed at knifepoint in his own home.
At around 9.30pm on Thursday 26 November 26, the 70-year-old man answered the door of his property in Rowland Street in Royston.
A masked man, who at first said he was from the police, threatened the pensioner with a knife before forcing him into his flat where the victim was bound by his hands and feet and his mouth was covered.
The offender then stole a quantity of cash and a mobile phone.
The 70-year-old man shouted for help but was not heard until the following morning when the police were called.
The victim was taken to hospital where he is in a stable condition.
The offender is described as white, around 5ft 6ins tall, with a local accent. He was wearing dark clothing.
Police are asking for anyone who was in the Rowland Street area on the evening of Thursday 26 November 26 and who may have seen anything suspicious to come forward.
Anyone with information is asked to contact 101 quoting incident number 242 of November 27 2015.