(ANSA) - ROME, APR 29 - Andrea Sempio killed Chiara Poggi, a 26-year-old economics graduate stabbed to death at Garlasco near Pavia in August 2007, on his own, prosecutors in Pavia said Wednesday after summoning him to be questioned on May 6 after one of Italy's most sensational murder cases was reopened. It had previously been suggested that Sempio may have acted with others or with her ex boyfriend Alberto Stasi who is currently serving time for the murder. DNA compatible with that of Sempi...