There have been a series of convenience store robberies in Great Holm, Bradville and Downsbarn over an eight-day period.
The first offence took place on Tuesday, May 20 at Bradville Premier stores at around 11.15am.
Then there was another on Saturday May 24 at Downs Barn Londis store at 8.30 am, and finally the last robbery happened on Wednesday, May 28 at Londis Store, Great Holm, at 8.20pm.
The offences are thought to be linked as the same modus operandi has been used throughout the series.
The offender enters the shop and then walks around the outside aisles before producing a knife to staff members and demanded money from the till.
The offender is described as being his mid twenties or early thirties, of slim to medium build, and between 5ft 7ins to 6ft tall.
Investigating officer, Det Sgt Phil Turner-Robson from Milton Keynes Force CID said: “It is important that all shop owners know to report any criminal offence to us immediately.
“In the case of robbery it’s important that we attend the scene straight away in order to ensure that we can gather the appropriate evidence.
“We are thoroughly investigating this crime series, and we ask that anyone who has any information reports it.”
> Officers in Milton Keynes offer the following advice:
Ensure that you CCTV footage is in full working order
Ensure that only a minimal amount of cash is kept in the shop till, and that the remainder is kept in an insurance approved safe
Look out for any suspicious behaviour outside of the shop
Anyone with information should contact the Force CID at Milton Keynes police station via the Thames Valley Police Enquiry Centre on 101.
If you don’t want to speak directly to the police, you can contact the independent charity Crimestoppers anonymously on 0800 555 111.
No personal details are taken, information is not traced or recorded and you will not go to court.