Witness: Zaldy Co’s alleged kickbacks have acknowledgment receipts. MANILA, Philippines — The alleged kickbacks delivered to former Ako Bicol party-list Rep. Zaldy Co from state witness and former Department of Public Works and Highways (DPWH) engineer Henry Alcantara have acknowledgement receipts (AR), a witness told the Sandiganbayan Third Division on Thursday. Wirt Walter Rosales, personal assistant of Alcantara, made this revelation when he testified during the bail.