Got a complex problem on my hands

[Simon Renshaw]

Hi,
 
I have 2 devs working in the same repository. Dev1 made a pretty big mistake 
and asked me if it was possible to revert all the files he modified back to 2 
days ago (Monday) without touching to the files that dev2 modified. And this is 
for everything in that repository.
 
I know how to revert everything to a specific day but I do not know how to only 
revert files checked in by a specific dev.
 
What are my options?
 
Thanks!
Simon