The director of the Reston Zoo was arrested Friday after a sick wallaby was allegedly treated improperly, authorities said.

Meghan Mogensen, 26, of Silver Spring, was charged with animal cruelty and possession of a controlled substance, according to the Fairfax County Police Department. The arrest came after a five-month investigation.

Animal Control officers were notified of a situation at the zoo when they followed up on a complaint about suspicious circumstances surrounding a wallaby's death. Officers opened an investigation about allegations of improper treatment of injured animals and euthanasia drug use on Jan. 26, and a search warrant was executed on Feb. 16.

NBC Washington reported that the investigation found that the zoo didn't have the necessary permits or training to use a euthanasia drug on the wallaby.

Police are continuing to investigate the incident.