There are two main types of testimony given by professionals at a trial, deposition, or hearing:
Technical or scientific witness testimony
Expert witness testimony
Digital forensic practitioners may be called upon to act in either or both roles. The technical or scientific witness provides evidence of facts that were uncovered during the investigation and describes what was found and how it was obtained. The expert witness provides opinion about what was observed based on experience, using deductive reasoning with observed or examined facts.
It is important to reiterate that in presenting a report or testifying in person, the practitioner must ensure that exculpatory as well as inculpatory evidence is presented to the other party. The practitioner must make the following things certain when presenting the evidence:
Conclusions are technically sound
The evidence solidly supports them and is properly preserved
Any exculpatory evidence that may have been found...