Said Machaouat, 27, hides his face as he is driven away. He said that he wanted his target to be about the same age as him

A drifter suffering from depression after his wife left him has said that he studied passers-by from a bench in Turin for 20 minutes before fatally stabbing the one who looked the happiest.

Said Machaouat, 27, a Moroccan-born Italian citizen who lived in a homeless shelter, said that he chose Stefano Leo, 34, because he looked “happy and serene”. He walked up behind Mr Leo and stabbed him in the neck. He gave himself up after police tracked him for weeks following the murder on February 23 on a busy path by the Po river.

Paolo Borgna, the magistrate who interrogated Machaouat, said that he was horrified by the motive. “I made him repeat it twice because it didn’t seem possible,” he said. “I still