D.C. Code § 42-3108: Burden of proof.

The plaintiff must establish that a drug-, firearm-, or prostitution-related nuisance exists by a preponderance of the evidence. Once a reasonable attempt at notice is made pursuant to § 42-3103, the owner of the property shall be presumed to have knowledge of the drug-, firearm-, or prostitution-related nuisance. A plaintiff is not required to make any further showing that the owner knew, or should have known, of the drug-, firearm-, or prostitution-related nuisance to obtain relief under § 42-3110 or § 42-3111.