The JonBenét detective who went to his grave fighting for the Ramseys to be cleared

Veteran detective Lou Smit came out of retirement at the request of Boulder authorities after JonBenét Ramsey’s murder – but quickly came to believe that her family did not kill her. Smit resigned but kept investigating, his loved ones taking on the mission after his 2010 death – and a new Netflix documentary highlights much of Smit’s work, writes Sheila Flynn