Authorities say they have dismissed their case against a 43-year-old Maryland man accused of paying people to draw their blood and storing it in large quantities in an abandoned warehouse in Washington.

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The Washington Post reports that local prosecutors dismissed, without prejudice, the charge of practicing registered nursing without a license against Khoa Hoang Nguyen on Thursday. That means prosecutors could refile the charge of additional charges could be filed later.

Nguyen was arrested in May after a Metropolitan police officer saw people congregating in front of a Washington apartment building. An affidavit said the officer investigated after overhearing people discussing people paid for giving blood.

Court documents said Nguyen told police he was certified and working for a biomedical company.

Nguyen's attorney and prosecutors have not commented further.