The Mito District Court has found a 40-year-old former employee guilty of murdering two residents, aged 84 and 76, by injecting air into their veins through IV tubes at a senior citizen facility in Koga City, Ibaraki Prefecture, six years ago. On the other hand, he was acquitted of the murder charge against another 84-year-old resident, saying, ``There remains a reasonable doubt that the defendant was the culprit.''