A boy who died of scurvy was "invisible" to the authorities despite concerns being raised about his welfare, according to a leaked official report.
Eight-year-old Dylan Seabridge, who was home-educated, was rushed to hospital after collapsing at his home in Eglwyswrw, Pembrokeshire, in December 2011.
His parents Julie Seabridge, 47, and her husband Glynn, 48, were charged with child neglect but the Crown Prosecution Service (CPS) later dropped proceedings against them.
Now it has emerged that concerns about his welfare had been raised more than a year before his death, and while education officials visited the Seabridges, they had no power to see Dylan.
A draft serious case review report leaked to BBC Wales said Dylan was effectively "invisible" to the authorities and concluded that rules on home education needed to be strengthened as a matter of urgency.
At an inquest last year, a coroner was told his parents had not sought medical attention for Dylan because they believed he was suffering from growing pains.
But a Home Office pathologist said Dylan had died due to vitamin C deficiency, commonly known as scurvy, an illness associated with poor diet. Symptoms include lethargy, spots, spongy gums and bleeding from the nose.
The inquest took place after the CPS decided not to pursue criminal proceedings against Dylan's parents following "a detailed review".
District Crown Prosecutor for Wales Iwan Jenkins said: "It is our view that Julie Seabridge is unfit to face criminal charges on health grounds.
"In relation to Glynn Seabridge, our conclusion is that it is not in the public interest to pursue a prosecution against him.... these are related to concerns about his health and the likely effect of a prosecution on him, as well as the nature of the case and the likely penalty that a court would impose in the event of a conviction."
The death of home-schooled Dylan has prompted calls for a mandatory home education register in Wales.
The Welsh Government said it would publish guidance on the issue soon.
A spokeswoman said: "Following a thorough consultation in 2012, the Education Minister decided not to proceed with legislation in this Assembly term.
"Instead, the Minister asked for information and guidance on elective home education to be improved and the Welsh Government subsequently commissioned research to inform new non-statutory guidance for local authorities.
"The guidance ... will be published shortly.
"The guidance makes it clear that, where possible, local authorities should seek the views of home-educated children and young people."
NSPCC Cymru said it had long supported registration for children who are educated at home.
A spokesman said: "Every family has a right to choose how to educate a child and home learning alone is not a risk factor for abuse or neglect, but it is important to ensure that they do not fall off the local services radar."