KORONADAL CITY - After a week-long surveillance, police in Tantangan, South Cotabato arrested over the weekenda couple believed to be engaged in illegal drug pushing.Chief Inspector John Erick Medel, Tantangan town police chief, identified the couple as Leonardo Abuan, a retired official ofpolice investigation unit in the province and his live-in partnerEmily Taberdo, both of Purok Sampaguita, Barangay Poblacion.After police agents managed to secure shabu from teh couple, an operation, PROJECT Double Barrel, was carried out.Medel said Tadero was included in the police watch list. A cal.