The 56-year-old owner of a restaurant in Berlin-Steglitz was seriously injured by stab wounds on Monday afternoon.
The alleged perpetrator – a man he knew – first knocked in vain on the glass door of the restaurant and then kicked it in, the police said on Tuesday.
The 44-year-old is said to have demanded money and stabbed the torso of the local owner, as a friend of the 56-year-old told the police, who is said to have witnessed the situation.
The innkeeper was taken to hospital by paramedics. The suspect was arrested two hours later, it was said, he had first fled on foot and then by car without taking anything.
An acquaintance of the seriously injured man then informed the police that the suspect had threatened him by phone and was on his way to him.
The emergency services found drugs and a knife on the 44-year-old, which were confiscated as alleged crime equipment. He was taken into police custody.