The “DA” is the initials of Moore’s then legal secretary. The signature is a facsimile that she would attach to his legal documents.
Such was the instance involving the case of one of Moore’s accusers, in which he represented the accuser’s mother in a custody battle for a grandchild. The court found in favor of the mother, who was then awarded custody of her grandchild. There’s your motive.
Seems to have backfired in Moore’s favor now!