In this paper a cyber-forensic framework with a detailed guideline for protecting control systems is developed to improve the forensic capability for big data in critical infrastructures. The main objective of creating a cyber-forensic plan is to cover the essentials of monitoring, troubleshooting, data reconstruction, recovery, and the safety of classified information. The problem to be addressed in control rooms is the diversity and quantity of data, and for investigators, bringing together the different skill groups for managing data and device diversity. This research embraces establishing of a new digital forensic model for critical infrastructures that supports digital forensic investigators with the necessary information for conducting an advanced forensic investigation in Critical Infrastructures. The framework for investigation is presented here and elaborated. The extended work applies the framework to industry case studies and is not reported here.