The mysterious cocaine discovered in the West Wing over the weekend was reportedly found in an area that the White House uses to store guests’ cellphones.

Guests who go through security on visits to the complex are asked to leave their phones in small boxes. The drug was found near those boxes, according to reports from The Washington Post and CBS News.

How an illegal drug showed up in the part of the White House complex that includes the Oval Office and offices for key staff and aides is a big Washington mystery this week.

The White House was evacuated Sunday evening after the Secret Service discovered a powdery substance.

Secret Service agents were doing routine rounds when the substance was found in an area of the West Wing that is accessible to tour groups.

Firefighters and emergency crews arrived and performed a field test, which preliminarily identified the substance as cocaine.

The Secret Service said the drug did not pose a threat, and the complex was reopened later that evening.

President Biden and his family, including the president’s son Hunter, left the White House Friday for Camp David. Mr. Biden and his family returned to the capital on Tuesday for Independence Day celebrations.

The Post report said staffers can give West Wing tours, which sometimes occur on nights and weekends.

The guests can view the ground floor and the first floor of the West Wing and get a glimpse of the Oval Office, Cabinet Room and the Roosevelt Room.

• Alex Miller contributed to this report.

• Tom Howell Jr. can be reached at thowell@washingtontimes.com.