First Minister Carwyn Jones has apologised to the parents of Robbie Powell, who died more than 20 years ago following a "catalogue of errors".
Mr Jones was making a statement on the latest in the investigation into his death, on 17 July 2012.
Robbie Powell from Ystradgynlais died from a rare hormonal condition in 1990 after a test to diagnose the disease wasn't carried out.
An inquest in 2004 into his death at Morriston Hospital, Swansea, in April 1990 returned a verdict of death by natural causes aggravated by neglect.
His father William Powell has campaigned for a public inquiry ever since.
During the statement the first minister said that there were "sever failings in the care of Robbie" and that his family have been "let down badly".
However Mr Jones said a number of these concerns relate to actions taken by the police and Crown Prosecution Service that fall, respectively, within the remit of the UK Home Office and Attorney General's Department.
Both departments confirmed that they did not wish to join in establishing a joint inquiry into Robbie's case.
The first minister announced that he would to write to both Dyfed Powys Police regarding their "incompetence" as well as the General Medical Council regarding "why no action was taken" following Robbie's death.
He announced the publication of a report by an independent investigator on the lessons to be learned from the death of the ten year old boy, that included 12 recommendations.
These recommendations include ways of improving communication in care and dealing with complaints following the death of a patient.
Mr Jones said: "What we have seen is a catalogue of errors, a catalogue of bad luck and a catalogue of neglect."
He added: "This investigation's recommendations show us there are still some things we can do to further improve.
"I know you will share my determination to continue to learn - to provide a lasting positive legacy from Robbie's untimely death."
Members from across the Siambr welcomed the first minister's public apology for the Powell family..
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