The remains of Marian Partington's sister, Lucy, were found to be the cellar of the Fred and Rosemary West house 25 years ago.
She had been missing for over 20 years.
Marian, from Llanidloes, has spent her life reflecting and coming to terms with what happened.
Now she explains how, even after the horror of what her sister holds in the hands of the Wests, she found that she could forgive them about what they did.
Watch BBC Inside Out West, on BBC One, at 7:30 pm on Monday.