InfoSec: What job title fits these responsibilities?

Hey all. I understand that information security has become quite a broad field within IT with increasing importance -- my own company recently went from 3-4 security employees to over 25 in a matter of months!

However, I have an idea of a specific area of security that I would like to migrate toward, but have no idea what the demand for this is or what the job title would even be called...

I have a very strong enterprise Linux/UNIX administration background and realize that many large companies trust these operating systems to secure their most important data; however, as we see in the news, breaches happen daily.

At a previous company, we also experienced a breach of our web servers in our DMZ. As a result, the company called upon a security firm who sent out a consultant to gather information regarding the environment, the breach, logged events, etc. He performed an analysis based on this information and wrote up a report regarding the breach and suggestions on what took place, what issues he saw with the environment, and other follow-up actions.

He was on-site a couple days, got to be right in the action, and you can bet he was paid a boatload of money for his analysis. So... what role would this be? Are there many jobs out there in the infosec field that would be suited for a strong UNIX/Linux background?

Thanks in advance!