A robber targeted two H Samuel stores in one week last month in a crime spree that netted him jewellery and watches worth more than £5,000.
Both robberies took place in February with the first at the H Samuel in Lakeside shopping centre in Thurrock on February 21 and the second at an H Samuel branch on Chelmsford High Street in Essex on February 27.
Police are still hunting the man and have released a new CCTV image of him to try and locate him for questioning.
During the Lakeside robbery the man entered the store at about 5pm and opened a cabinet with an unknown implement and emptied it of 22 watches. He was challenged by staff but retaliated with verbal abuse.
At the Chelmsford store he entered the shop at 2pm and stole three gold bangles, again using an unknown implement to open up a locked cabinet.
Detective Constable Colin Marshall of Essex Police is the investigating officer on the case and is urging anyone with information about him to get in touch using the non-emergency police number 101.
Marshall has described the man as white and during a previous robbery he wore a brown and black hooded rain mac and a white check shirt.
Elsewhere in Essex, police are still searching for a man who stole diamond rings from Lance James Jewellers on Crown Street in Brentwood. The theft took place on January 27 and the man is described as being mixed race, about 30 years of age with dark hari, and he was wearing a dark cap, jeans and Nike trainers during the robbery.