When Japanese police detained and took a man into protective custody one evening in 2007, the officers on the scene were not aware he had an intellectual disability, nor that their decision to forcibly restrain him would contribute to the young man's death.

Nearly two decades later, the case of Kenta Yasunaga, who had autism, and his tragic death in police custody is the topic of a new Japanese documentary film, titled "On the Way Home," which seeks to explore what happened on that fateful evening. It also documents the subsequent criminal and civil lawsuits fought by his family in their quest to find out the truth about what happened, in the hope they may prevent such a tragedy from occurring again.

Sometime around 6 p.m. on Sept. 25, 2007, the 25-year-old was riding his bicycle home from a workshop he had regularly attended in Saga Prefecture, southwestern Japan, when police officers attempted to stop him, thinking he had been acting suspiciously.