A surfactant compound that police believe was used to kill two elderly male patients at a hospital in Yokohama may have been injected into intravenous drip bags through holes made in their rubber plugs, investigative sources said on Tuesday. Police found small holes in seals on the rubber plugs of multiple unused drip bags stored at a nurses’ station at Oguchi Hospital in Yokohama’s Kanagawa Ward, the sources said. The police checked around 50 drip bags that had not been used and discovered holes in the seals on the rubber plugs of about 10 bags, the sources said. Those bags include ones bearing the names of patients other than the two killed by poisoning, suggesting an attempt to kill patients indiscriminately. The police are investigating if those tampered bags contained surfactant compound. Sozo Nishikawa and Nobuo Yamaki, both 88, died of poisoning in the hospital on September 18 and 20, respectively, after medical drips were administered. There were no apparent holes or ruptures in medical drip bags attached to Nishikawa, in whose body a surfactant compound was found in an autopsy, the sources said. Nishikawa died on September 18 after a nurse found his heart rate was falling around 4.50pm that day, according to the police. He was hospitalised on September 13. The hospital initially concluded he died of illness. But the police decided to conduct an autopsy on his body after Yamaki was found to have died of poisoning last week. The two patients had been confined to their beds and medical drips including a nutrition supplement had been administered. The police are examining the inside of some of the drip bags attached to Nishikawa, although no holes were found, according to the sources. The police have detected a surfactant compound in one of the drip bags attached to Yamaki that is of the same composition as that contained in disinfectant stored at the nurses’ station on the fourth floor.