A Russian man convicted of killing a Swiss air traffic controller will not be freed from prison this week, Switzerland's highest court ruled Thursday, according to the DPA. Vitaly Kaloyev could have been freed Friday after a lower court decided to grant him parole. He had served two-thirds of a five-year prison term. Kaloyev was jailed in October 2005 for stabbing to death Peter Nielsen. Nielsen was on duty at Skyguide, the Swiss air traffic control centre, when a DHL cargo plane and a Bashkirian Russian passenger jet, carrying 69 people mainly school children, collided in July 2002 at Ueberlingen, near the Swiss-German border. The two crew of the cargo plane were also killed. The 51-year-old Russian held Nielsen responsible for the crash in which he lost his wife and two young children. He attacked the controller outside his home in Kloten in February 2004. The federal supreme court blocked his release on a legal technicality as two earlier appeals in the case were outstanding. Kaloyev's original eight-year sentence had been reduced to five years in June 2007 by a lower court in Zurich, the same court that then granted parole. The Zurich prosecutor has challenged both rulings.