Mr Kouzaris and his university friend Mr Cooper were found shot dead in an estate in northern Sarasota US police have released photos that two British tourists took of themselves while out drinking on the night they were shot dead in Florida.
University friends James Kouzaris, 24, from Northampton, and James Cooper, 25, of Warwick, were found dead in the city of Sarasota early on Saturday.
The photos of the victims were taken in bars in downtown Sarasota and police want to know what happened next.
A 16-year-old boy has been arrested in connection with the double murders.
Sarasota Police named him as Shawn Tyson and said he had previously been arrested for allegedly firing shots into a car on 7 April.
No murder weapon has yet been found but both men, ex-Sheffield University students, were shot a number of times, the BBC understands.
BBC Washington reporter Steve Kingstone said contrary to some reports, no bullet casings were found at the scene.
He said the 16-year-old had not been formally charged and prosecutors had until 8 May to decide whether to charge him as a juvenile or as an adult.
He said the expectation was that he would be charged as an adult.
Officers said there was no known link between the holidaymakers and the boy.
Officers said there was no known link between the men and Shawn Tyson Sarasota Police Captain Paul Sutton said: “It is very unusual to find tourists or visitors in this area. It is a residential neighbourhood with no shops and no bars. We do not know what brought them here at 3am.”
He said the pair may have been given a lift to Newtown by someone they had befriended, or they may have walked there, or hired a cab which police had not yet traced.
They had been staying about 12 miles away on the island city of Longboat Key with Mr Cooper’s parents Sandra and Stanley, who have now returned to the UK to their home in Hampton Lucy, Warwickshire.
Mr Kouzaris and Mr Cooper were found lying about 50ft apart near a housing estate.
The two Britons were not carrying drugs and there is no evidence they were drug users, police said.
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