But it is alleged that the son attacked his 79-year-old mother before she drowned.
Police and prosecutors in Muenster said on Tuesday that the autopsy showed the woman suffered head injuries before her body was lowered into the well.
Chief prosecutor Martin Botzenhardt said the 55-year-old is alleged to have killed his mother over inheritance disputes, Westfälische Nachrichten added.
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Authorities say the suspect hasn’t commented on the allegations.
Chief prosecutor Martin Botzenhardt said: “The man from Neuenkirchen is charged with drowning his mother in deep well water.”
The suspect appeared to have attacked her because she planned to sell parts of the land he hoped to inherit, Mr Botzenhardt added.
In a separate case, a farmer has gone on trial in Augsburg accused of drowning his wife in slurry last year to avoid splitting their assets in a divorce. The man’s lawyers deny the allegations.
Last year, 123 women in Germany were killed by their current or former partners.]
Additional reporting by Associated Press
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