Five months after he was found stabbed to death on a riverbank, detectives say they're still not sure whether high flying Durham solicitor Peter Maine was murdered or took his own life.
And now after months of exhaustive inquiries they're trying to trace three mystery figures who could hold the answers.
Watch Gregg Easteal's report here.
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The four people who were all related were killed on the A64 near Malton as they returned from a wedding in Leeds.
GMB's Ben Shephard is cycling, running and swimming from Whitehaven to Tynemouth to raise money for the Children's Heart Unit Fund (CHUF).
Grandfather Stewart Anderson, 54, died after an incident at Durham's Loveshack nightclub in Durham City