Armed thieves wearing balaclavas stole tobacco and cash from the same Co-op store in Colchester in two separate incidents three months apart.
The first incident at the shop in Old Heath Road happened shortly before 9pm on October 13 last year, Essex Police said.
Three men wearing balaclavas – two of whom were armed – ordered a staff member to hand over money while another was instructed to get packets of cigarettes.
Both members of staff complied and the men left with items worth a total value of between £2,000 and £4,000.
The suspects left the scene by running through Cavendish Avenue before getting into a car and driving off towards Barn Hall Avenue.
In the second incident, which took place at the same location on January 16 this year, two balaclava-clad men entered the store with a crowbar.
They attacked a shop worker and left with more than £4,000 in cash and more than £1,000 worth of tobacco.
Police have linked these incidents to three further robberies at Co-op stores in Maldon.
On September 1 last year, a man wielding an axe stole between £2,000 and £3,000 in cash from the store in Wood Road.
On October 6 last year, three men – two of whom were armed – ordered staff in the Lawling Road store to hand over cash and cigarettes.
And on November 17 last year, three men entered the same Lawling Road shop and left with cash and cigarettes after threatening staff.
PC Alex Plakhtienko, of the Essex Police Business Crime Team, said: "These offences relate to a series of robberies during which violence has been used against staff members and a large quantity of cash and cigarettes were stolen.
"We are progressing a number of lines of enquiry and we have linked each of these incidents.
"We are now appealing to the public who may be able to identify the people pictured.
"I appreciate those who were seeking to identify have their faces covered but I would ask people to please look closely at the images to see if you might have any information which could help our investigation."
Essex Police is appealing for witnesses for the first incident, which has the reference 42/229698/21, and the second robbery, which has the reference 42/13445/22.
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