An independent inquiry is to be set up into the healthcare received by Kevin Hewitt - dubbed the 'eclipse killer' by local media.
Mr Hewitt, 31, battered 72-year-old William Marchant to death an hour before last year's eclipse because he believed the world was coming to an end.
At Nottingham crown court last week, he pleaded guilty to manslaughter on the grounds of diminished responsibility. He also admitted the attempted murders of a father and son.
Leicestershire health authority said a timescale had not been set for the investigation, but it would be held in accordance with Department of Health guidelines to examine 'all circumstances' surrounding Mr Hewitt's treatment.
The court was told that Hewitt - diagnosed with schizophreniahad received psychiatric treatment in 1991 at the Arnold Lodge unit in Leicester, and had been treated for nearly two years at Leicester Royal Infirmary, before being discharged last year after 'effective treatment'.