My guess is it is the return line leaking fuel.
There is not really anywhere for the fuel to leak externally from an injector that I know of. Unless the injector is fallng apart which I seriously doubt.
I could be wrong here as i do not know your year and make but on my two cars it is always the return line that is leaking.

__________________
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique