Local prosecutors dismissed their case Thursday against the 43-year-old man accused of paying people $30 to draw samples of their blood and storing it in “large quantities” in an abandoned apartment near Nationals Park in Southwest.

Khoa Hoang Nguyen had been charged with practicing registered nursing without a license. Prosecutors from the District’s Office of Attorney General dismissed the charge a day before Nguyen was scheduled to appear at a D.C. Superior Court hearing.

Nguyen, of Rockville, was arrested in May after a D.C. patrol officer stumbled on the alleged makeshift blood-drawing operation when a patrol officer saw people — many described in court documents as “habitual substance abusers” — congregating in front of a brick apartment building at P and First streets.

A D.C. police officer overheard some of them discussing being paid to give blood, according to the affidavit filed by the Office of the D.C. Attorney General, and investigated. Nguyen told police that he was doing work for a biomedical company “and that he was approved and certified to withdraw blood from citizens,” according to court papers. A woman at the apartment told police that she and Nguyen had drawn blood from 20 people on one day and that Nguyen had a ledger with an additional 205 names.

The charge was dismissed without prejudice, meaning it could be refiled or that additional charges could be filed at a future date. A spokesman for the prosecutor’s office declined to comment further on the case. Calls and emails to Nguyen’s attorney were not returned Thursday.

Khoa Hoang Nguyen declined to comment as he was leaving court May 25 after his initial appearance. (Keith Alexander/TWP)