The 88-year-old care home resident in Graz told police that she had carried out the attack on Friday because she had been disturbed by the frequent shouts of her roommate.
The OAP had then got a glass bottle and hit the other resident, later telling police she was “happy” when the roommate was quiet after the attack.
After carrying out the attack, the 88-year-old then went back to bed, with an employee of the care home discovering the injured woman a short while later.
The 86-year-old was rushed to hospital but died there within an hour and a half of arriving.
Head of police in Styria Fritz Grundnig told APA that the suspect, who admitted to the attack on Sunday but cannot remember the incident in full, is currently being held in a psychiatric institute. She is being brought before a judge on Monday.
According to the care home, the suspect has psychiatric problems, which is likely to be confirmed by legal experts.
The care home director on Saturday that he was dismayed but would make no further statement, saying: "This is tragic enough."