Police investigating the shooting of hero shopworker Colin Thomas have focussed their attention on how the suspects escaped.
Officers have renewed an appeal for information, particularly anyone on the Purley Way who may have seen the suspects leave the scene on Thursday, September 17.
Detective Superintendent Bob Cummings from the Flying Squad said, as a result of media appeals, the team had received many calls from members of the public who were using the store that day.
He said: "I am also anxious to trace anyone who may have seen anything of the suspects as they ran from the store across Purley Way.
"We don't know if they had parked a getaway vehicle there or maybe had a driver waiting for them. It's also possible there were two vehicles as there were five suspects to be carried.
"Purley Way is a major road in south London and at that time of the evening it would still have been very busy, especially in that area where there are several large retail premises.
"Were you in the area of Purley Way, between 7pm and 8pm Thursday, September 17? Did you see or hear anything suspicious? Did you see one or two cars driving along Purley Way at high speed, around 7.40pm that evening?"
Police were called at 7.45pm on Thursday, September 17 to reports of a person shot at Costco in Imperial Way, Croydon.
Officers and London Ambulance Service attended, and 24-year-old floor supervisor Colin Thomas from Peckham was taken to a south London hospital suffering a gunshot wound to his body.
He remains in hospital in a condition described as serious but stable.
It is believed five suspects, all described as young black men, wearing dark clothing with their faces covered, entered the store.
Two waited at the entrance while the other three smashed a jewellery display cabinet and stole several items.
This activated an alarm, which brave Mr Thomas responded to.
As he pursued the suspects fleeing the store he was shot by one of the suspects who had waited at the entrance.
All the men then ran away from the store.
Any witnesses or anyone with any information is asked to call the Flying Squad on 020 7232 6530 or Crimestoppers anonymously on 0800 555 111.
There have been no arrests.
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