“It’s a mystery, it’s a nightmare. Where on earth is he?”
She added: “The thing about my dad, he’s always saying things like life is a series of challenges. He’s spent his life trying to help people - what’s happened to him is so devastating and so unfair.
“None of his things have been found. That’s so weird. The police said they got the special sniffer dog in, there’s only a few of them in the world. We were really afraid he had gone down to the lake or been taken by somebody down to the lake, but there’s no scent on the lake.”
His wife, Shirley, added: “I believe in my heart he’s still up there. If anybody has seen him after 3pm on Friday, please let us know.”
The missing walker is of large build, around 5ft 9ins, and wore glasses, a checked, short-sleeved shirt and beige shorts.
An appeal for information has also been posted on www.missingabroad.org/missing-profile/felix-marr.