Jordan Burling was "invisible to the authorities".
The young man had a very troubled life but only had minimal contact with state agencies, including the education system.
Prosecutor Nicholas Lumley QC told Leeds Crown Court: "We do not pretend that Jordan Burling had an especially healthy or happy life, even in his early years."
The court heard that he attended his local primary school, where he soiled himself and defecated on the floor.
Teachers noted he had head lice and his teeth were in a very poor state.
Soon after he went to Farnley Park High School, his mother wrote to the council telling them that he was going to be educated at home.
He was "home-schooled" from the age of 12, jurors were told.
"He never attended school or college again, never took any examinations or achieved any qualifications," Mr Lumley said.
"Nor did he ever work, as far as can be ascertained.
"From the time Jordan was taken out of school, he became increasingly anonymous. Education and social services played little part in his life."
The jury was told that Jordan (pictured) had not been seen by the family doctor for years before he died.
And he had not seen a dentist since 2009, when 16 of his teeth were treated, including four extractions.
Mr Lumley said: "He only really had contact with his immediate family.
"He may have been invisible to the authorities but not so to these defendants."
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