Dabron Sashenstar is the brother of Aldeth Sashenstar and head of the Merchants' League Estate. If you helped Aldeth in the first Cloakwood area then Aldeth will be waiting outside the Merchants' League Estate waiting for you and will ask you to investigate his company. If you killed Aldeth, then Dabron will attack you in Baldur's Gate Central. He will drop the Heavy Crossbow of Accuracy.