You can search for contributors in the Sandbox by clicking on the CONTRIBUTORS search tab in the upper right-hand corner of the screen, and using the search box in that tab.
The CONTRIBUTORS search box searches the following fields in contributor profiles: First Name, Last Name, Institution.
When searching by name, you can search by First Name, by Last Name, or by First Name followed by Last Name (without quotation marks). Please note that phrase searching for names (i.e., using quotation marks around full names) does not work in the CONTRIBUTORS search box.
In addition to searching for contributors, you can browse the directory of contributors in the Sandbox.