Three expert witness are left to argue how Olivia Hope's hair got on Scott Watson's boat

Watson, who's in jail for murdering Hope and Ben Smart in 1998, is currently making his second attempt before the Court of Appeal this week.

Strands of Hope's hair found on Watson's blanket, is a focal point of the appeal.

Open Justice reporter Catherine Hutton says a forensic scientist argued her testing was careful to avoid contamination.

But she says the hair could have reached the blanket another way.