On Monday, the trial started in a Saarbrücken courthouse.
The defendant is facing charges of bodily harm with fatal consequences.
Both the victim and the perpetrator lived in the German town of Perl, not far from Luxembourg, and worked in the Grand Duchy.
The victim, a 52-year-old woman, and her husband were regarded as pillars of the community by their neighbours.
However, tensions regularly ran high between the middle-aged couple and one of their neighbours.
After several years of animosity, things came to head in November 2017 when the victim was pushed by her neighbour and hit her head.
Her injuries were so severe that she passed away in hospital two days after the altercation.
