The US Secret Service is investigating how cocaine came to be found at the White House on Sunday night.
The discovery led to a brief evacuation of the White House; President Joe Biden and his family were at Camp David in Maryland at the time.
The fire department was called in to test the substance to determine it was not hazardous, and the initial test returned positive for cocaine.
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A secondary, more sensitive lab analysis confirmed the results, The Washington Post reported.
The substance was found on the ground floor of the West Wing, where the Oval Office and working spaces for the presidential staff and aides are located.
A senior law enforcement official told CBS News the powder was found in a zip lock bag in a storage room regularly used by staff and visitors to store mobile phones.
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Press secretary Karine Jean-Pierre said President Joe Biden has been briefed on the incident, and the Secret Service will lead a full review into how the substance got into the White House.
Jean-Pierre said the location where the powder was found is a 'heavily travelled' part of the White House.
"When it comes to visitors to the West Wing, they come for many reasons, obviously we do have West Wing tours that occur here on campus," she said, adding tours took place Friday, Saturday and Sunday.
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"The president thinks it's incredibly important to get to the bottom of this.
"We have confidence that the Secret Service are going to get to the bottom of this," she added.
While the Secret Service is not ruling out any White House staff, guests or visitors, the leading theory at the moment is that a guest brought in the bag on a West Wing tour.
The Secret Service is currently combing through visitor logs and security footage as part of its investigation.
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