Police from the city of Ostroda, northern Poland, found the bodies of a 49-year-old woman and a 57-year-old man in their flat on Wednesday.
Forensic investigators, based on the evidence secured at the scene and the way the bodies were found, provisionally determined that a third party contributed to the death of the couple.
The police immediately launched a search for the married couple's daughter who lived with them.
The daughter was arrested on Thursday in a nearby town, the Ostroda police reported. She will face double-murder charges and could get a life sentence if found guilty.
The couple was found after a relative called the police, concerned that the man had failed to appear at work that day.
The bodies were lying on the floor with cuts and stab wounds. (PAP)
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