A 15-year-old boy was found in possession of thousands of pounds in dyed notes on Wednesday.
Officers from the Operation Aries team received information leading them to believe the teenager had the money hidden away in his property from a cash-in-transit robbery.
A warrant was secured for his arrest and for a search of the property was conducted, eventually uncovering the haul hidden behind a washing machine.
The boy, who can’t be named for legal reasons denied having anything to do with the money.
Sergeant Darin Birmingham said: “This boy is on the fringes of gang membership and serious criminal activity. We have spoken to his mother in the past and she is at her wits end.
“We went around to the house to send a clear message, we will not tolerate crime being committed by anyone in the borough and those handling stolen cash, or indeed committing robberies will be swiftly arrested and dealt with severely."
Sgt Birmingham’s gang unit works very closely with parents who think their sons or daughters are part of a gang.
He added: “Our main task in the gang unit is to make the streets of Croydon safer for law abiding citizens.
"Of course we won’t think twice about arresting someone but there also have to be alternatives available to them.
"By working closely with schools, colleges and prisons we are able to follow those convicted through the courts and their imprisonment and try and give them a choice once they are back out."
Robberies in Croydon have fallen dramatically in recent months after pro-active operations were launched to tackle the growing problems of youth violence in the borough.
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