It was greed and a need to finance his gambling problem that drove the unnamed man to murder his 31-year-old friend and steal her money, said chief judge Ralf Peters on Wednesday.
According to the final verdict, his victim had refused to lend the accused money.
Enraged, the man grabbed a kitchen knife and stabbed the woman repeatedly while the victim’s daughter looked on.
After the murderer fled, the girl sat for another six hours at her dead mother's side.
"For the daughter the consequences of this deed cannot be forseen," said Peters.
Throughout the trial the man continued to protest his innocence, but judges found him guilty of murder and sentenced him to life in prison.
The court heard how the man's gambling meant he had constant money issues.
On the day of the murder in May 2013, the suspect said his car insurance payment had been overdue and his pregnant partner had wanted to go food shopping.
He told the court he had gone to visit the 31-year-old mother at home in the southern town of Mössingen, Baden-Württemberg, as she and her husband had often lent him money.
The man claimed he then had a chat with the woman and that they drank coffee together. Not long after, she had fetched a €500 note and lent it to him.
He said goodbye and left, he claimed, not realizing for another two weeks that the woman had been murdered the same morning.
But the man was unable to give the judges a convincing explanation of why his fingerprints and traces of his blood were found at the crime scene. He also contradicted himself in his testimony too often, judges found.
Judges said the evidence was enough to dismiss the fact that the man had a twin brother, making it impossible for investigators to unequivocally identify the source of the fingerprints and blood traces.
The convicted man was in tears as the sentence was read out. In his closing statement he again stated his innocence, accusing the investigators of sending an innocent man to jail.
He also blamed the authorities for the death of his unborn child - his then heavily-pregnant partner had a miscarriage when she was interrogated by police.
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