Christian's background stems from the academic world where he held a position as senior sysadmin for several years. During this time he also actively performed CERT duties. Christian has been active as a forensic IT investigator since 2004. He leads and actively participates in (digital) forensic IT investigations. Christian has a broad knowledge-base of operating systems and network protocols. He regularly gives presentations on the subject of IT security and IT forensics. As a teacher he also lectures on the subject of open-source intelligence using Internet sources. As an expert witness he is called upon to provide expert testimony in court on occasion. Working for both law enforcement and the private sector his experience in Forensic IT is broad.