The decedent’s will stated that after paying estate expenses and making certain bequests, the remainder of his estate was to be distributed to the residual beneficiary named in the will. However, no residual beneficiary was named in the will. The decedent’s two prior wills provided substantial bequests to his friend, Richard Knupp. Milton Schober, the attorney who drafted the decedent’s wills, submitted an affidavit to the trial court, stating that the decedent told him to name Knupp as the residual beneficiary in the decedent’s most recent will, but that Schober had mistakenly failed to do so. The trial court held that it could not insert Knupp’s name into the will, and that the decedent’s residual estate therefore escheated to the District of Columbia. Knupp appealed, arguing that extrinsic evidence showed that the decedent intended his residuary estate to go to Knupp, and that Knupp’s name was omitted from the will by mistake.