You could find out (Deal with taking resumes and the BS that accompanies that; liars, morons, etc to find the few that are actually golden in their field) by posting a req on a job forum like
Dice.com - Job Search for Technology Professionals
Another thought, as this may be an issue, is to get two people. One can cover your app and another the systems. However, realize if you get one person, you will be in this remarkably bad position again. Any critical role should have at least two people performing it, as if one person leaves, you are up a creek without a paddle.
These people may exist, but prepare to pay for them. However, a job that is this important may be worth it, as without them, what will you do?
Is this a small company? Have you considered getting consultants until you fill the role?