Mr Carruthers told MSPs the care system had never taught him enough home skills and he was "young andnaive" and did not have the essential skills to live alone when he left care.
They did not approach police in the UK until 10 months after the supposed "accident" because they were "young andnaive" and "intimidated" by Mr Sapstead, the court heard.
"This is not some naive, optimistic young man who has inherited a fortune and is about to blow it on some fantasy project on the north coast, " Mr Shaw said.
"When you're young, you're probably a little bit more naive to the inequities and injustices that really do exist in the world and why they matter, " said Wright, who lives in Boston.