Reliability assessment of digital forensic investigations in the Norwegian police

This case study presents a qualitative assessment of the reliability of digital forensic investigation in criminal cases in Norway. A reliability validation methodology based on international digital forensic standards was designed to assess to what extent those standards are implemented and followed by law enforcement in their casework. 124 reports related to the acquisition, examination, and analysis of three types of digital data sources - computers, mobile phones, and storage devices were examined. The reports were extracted from the criminal case management system used by the police and prosecution services. The reports were examined on technology, method, and application level in order to assess the reliability of digital evidence for criminal proceedings.

The study found that digital forensic investigation in 21 randomly sampled criminal cases in Norway were insufficiently documented to assess the reliability of the digital evidence. It was not possible to trace the digital forensic actions performed on each item or link the digital evidence to its source. None of the cases were shown to comply with digital forensic methodology, justify the methods and tools used, or validate tool results and error rates.