The article discusses the credibility of the expert opinion from the perspective of forensic biomechanics. The expert report shall be professionally correct, transparent, reviewable and understandable to the court, the parties to the criminal proceedings and, where appropriate, to the public at the trial. The authors present general requirements for expert opinion and necessary input parameters for processing expert opinion in the field of forensic biomechanics. The materials for the forensic biomechanics review are obtained from the crime scene, the body of the deceased, the examination of the body of the living injured person, and contribute significantly to the conclusions of experts in health care, forensic medicine, medical reports, witness testimonies. the conclusion of biomechanical investigations can be refined today by means of a mathematical model and computer simulations. The expert opinion can thus express a probable conclusion about the possibilities of physical behavior of persons during the crime. Such a conclusion provides further relevant information for an objective decision in the case.