The director of the Reston Zoo has been arrested on a charge of animal cruelty, Fairfax County police said Sunday. They said Meghan Mogensen, 26, was charged “after alleged improper treatment of a sick wallaby.”

Wallabies belong to the kangaroo clan, the National Geographic web site said.

Police said in a statement that the arrest followed a five-month investigation. They said they had followed up on a complaint of “suspicious circumstances” in the death of an adult wallaby.

Mogensen could not be reached for comment Sunday.