On May 5, just after 12.30pm, police officers arrived to a property on Brierfield Close, Barnsley, and found 61-year-old Agita Geslere with serious injuries.
She was taken to Barnsley Hospital but died a short time later a post-mortem concluded that she died from multiple stab wounds.
Her son, 31-year-old Renars Geslers, of Hoyle Mill Road, was then charged with her murder.
He appeared at Sheffield Crown Court in October and denied her murder.
However he has now admitted her manslaughter due to ‘diminished responsibility’ which was accepted by the Crown Prosecution Service.
This was because medical reports showed he suffers from paranoid schizophrenia.
He will be sentenced on January 28.