In its strictest connotation, the application of computer science and investigative procedures involving the examination of digital evidence - following proper search authority, chain of custody, validation with mathematics, use of validated tools, repeatability, reporting, and possibly expert testimony.
CNSSI 4009-2015 from DoDD 5505.13E
See digital forensics.
CNSSI 4009-2015 under computer forensics
The application of science to the identification, collection, examination, and analysis, of data while preserving the integrity of the information and maintaining a strict chain of custody for the data.
NIST SP 800-86 under Digital Forensics
The process used to acquire, preserve, analyze, and report on evidence using scientific methods that are demonstrably reliable, accurate, and repeatable such that it may be used in judicial proceedings
NISTIR 8006 under Digital forensics from SWDGE v2.0