He's been tweeting his support for the campaign to find her as her churchgoing father marks 2,000 days since the 35 year old disappeared.
The chef was last seen leaving work at York University in March 2009.
Her father, Peter, said: "It's more than frustrating.
"It's very difficult to live with because every day you're wondering what on earth happened.
"For 2,000 days I've been trying to get people to imagine how long that is...it's so difficult to imagine it going on that long."
Two men have been arrested and bailed in the last few months by police investigating her disappearance but they still don't know what happened to Claudia.
Peter is renewing his call for anyone who has any information relating to her disappearance to come forward.
You can contact the Missing Person's helpline on 116 000.
Hear more from Peter talking about the importance of prayer in this situation: