The 34-year-old Turkish teacher, identified only as Mehmet K, had apparently carried out the vendetta in order to salvage his honour. The father of four, whose wife is expecting their fifth child, blamed the girl's family for his disgrace, and his exile from the north German town of Bielefeld.
Mehmet K had been a respected leader of the Turkish community in Bielefeld, until rumours surfaced that he was seeing too much of a pupil named Zubeyde, then aged 18. The teacher went to Zubeyde's family, offering to make her his second wife.
Polygamy is practised in the remotest parts of Turkey, but is virtually unheard of in Turkish communities in Germany. Zubeyde's family refused, alerted the mosque, and as a result Mehmet K was sacked from his job and driven out of town.
That might have been the end of the story, but the fallen holy man was unable to accept it, and on Tuesday evening he returned to Bielefeld to wreak his revenge.
Shortly after 9pm, Zubeyde opened the door of her family's flat in a six-storey block to find Mehmet K standing outside. He said nothing, pulled a revolver and shot her. He then went into the living room and shot the three men sitting there. Three female members of the family tried to barricade themselves in one of the bedrooms, but Mehmet K dragged them out screaming, and shot them. All but one of the seven victims died instantly. Zubeyde's 17-year- old sister was resuscitated by doctors at the scene, but died of her wounds yesterday evening.
Mehmet K fled from Bielefeld, chased by police. Yesterday morning, his body was found near his new home in Tubingen, south-west Germany. He was slumped over a gun in his car, with a hole through the head.
Investigators said the death toll could have been much higher, because 13 people were staying in the flat when the teacher burst in. But Zubeyde's mother, her three youngest children and two grandchildren managed to run away.