LOR from Mentor

My mentor happens to be a world renowned researcher(MD/PHD), even though I didn't meet him in an academic/professional setting, he is willing to write a letter for me. Can this letter carry any weight in the admission process? What would it even be considered if I did use it? Help. Sidenote: He is the senior advisor/prof for the COM at the state school I graduated from
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Source Type: forums