Once a breach has occurred, it's very important to know about it.
Not only does a company need to know that it occurred, but it also needs to know the scope of the damage. Was data stolen? Were files damaged?
Was a back door installed that will facilitate future breaches?
This is the forensic part of information security.
Describe a topic that you think would make a good episode of a crime drama like CSI.
How would the main character go about solving the crime and identifying the perpetrator.