A 13-year-old boy is alleged to have killed a homeless man in the western German city of Dortmund, police and the public prosecutor’s office said on Friday. A mobile phone video shows how the child allegedly stabbed the man with a knife on Thursday evening. The autopsy revealed that the 31-year-old victim had been killed by several stab wounds. It is certain that the fatal stabs were inflicted by a child “under the age of criminal responsibility.” There had been a verbal argument between the victim and the child beforehand. There were also corresponding statements from three other minors, who …