CASTLE ROCK, Colo. (CBS4) – Police have arrested a former officer on the run now accused of robbery. They were able to track him down because of the tiniest pieces of evidence he left behind.

Former Sioux City, Iowa officer, Scott Allen Brasselero, 46, of Pueblo, is accused of robbing the Key Bank in Castle Rock. After robbing the bank police said Brasselero ran over to a Walmart parking lot, got into a vehicle and fled. He was eventually caught because of a piece of a Band-Aid he left behind.

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Brasselero apparently handed the bank teller a note demanding money.

“Shortly after that he’s running back towards his vehicle, gets back into the vehicle, and drives away,” a detective told CBS4. “When the male first came into the bank the teller had identified he had something covering his nose, which appeared to be a bandage.”

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Surveillance video from the Walmart showed where his car was parked, and when they searched the area police found a Band-Aid wrapper and a tissue.

“At one point the hood of his vehicle comes up and it appears as if he’s checking his oil, and so one of the tissues appeared to have an oil-like substance on it,” the detective said.

The evidence was tested and matched to Brasselero, who was wanted in several other crimes across the Front Range.

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Brasselero is currently being held in a Fremont County jail on a separate charge.