Google Product Forums
Re: Searching for 'Chris Hitchens' doesn't bring up page titled 'Christopher Hitchens'! How to fix?
Curry School of Ed
Google Custom Search
Indexing and Results
You can try adding synonyms in your control panel so that a search for "Chris" also searches for "Christopher" It's not ideal as you'd have to do it for each name, but in theory it should fix your problem.