"Despite having a broken leg and being on crutches, the woman waited until her son-in-law had fallen asleep and hit him several times around the head with the blunt side of an axe," regional investigators said in a statement.
The man was able to put a stop the attack, investigators said.
They did not give any information on the motive for the crime or the victim's condition.
The incident took place in February in Mariinsk, a small town in Russia's West Siberian Kemerovo region.
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