A former Swedish security officer, sentenced to life in prison for selling secrets to the Soviets, escaped during a leave from prison, officials in Stockholm said. Stig Bergling, 50, on a 24-hour leave from Norrkoping prison, was left alone with his wife in their suburban Stockholm apartment early in the week, officials said. When prison guards came to pick him up, Bergling and his wife were gone. Bergling, a security specialist and a U.N. officer then serving in the Middle East, was arrested by Israeli security officers on a visit to Israel in March, 1979. Six months later, a Stockholm court found Bergling guilty on charges of spying for the Soviet Union.