Find commandline which started a process

Question

I have a process Perl.exe which is running a script. I'd like to programatically find the name of the script being executed.
I know it can be done: Mark Rusinovitch in his ProcessExplorer finds that info in command which started a Perl's process. So I thought I'd be able to find it in System.Diagnostics.Process.StartInfo.FileName. Unfortunatelly it seems I am on a wrong track here - the two pieces of data which I am looking i.e .FileName and .Arguments are empty.
I'm fresh out of ideas, can someone suggests any alternatives what sould I try to get the info I'm looking for
Regards, Vladimir