An elderly Souderton man who admitted killing his wife of 59 years has been given 7 1/2 to 15 years in state prison. 81-year-old Rudi Koos pleaded guilty to third degree murder earlier this year, and Montgomery County Judge William Carpenter sentenced him Tuesday. He said he strangled his 75-year-old wife Waltrud “Trudi” Koos in January following an argument. Prosecutors say he told detectives he was in the kitchen watching TV when his wife entered and began laughing and calling him names after he accused her of having an extramarital affair. He said he pushed her, and then she scratched his face, and he pushed her onto the kitchen floor and choked her until she stopped moving. The couple had lived in the same West Broad Street apartment since they immigrated to the United States from East Germany in 1957.