Although mistake in identity (error in persona) and mistake in the blow (aberratio ictus) are two closely interrelated concepts they diverge from each other in terms of legal consequences to a considerable extent. Because mistake in the blow, as different from mistaken identity, is taken into consideration in determining the criminal liability of the perpetrator. However, the question of how to determine the demarcation line between these two concepts brought along many discussions up to today. In this study, we will first examine the views on this issue. However, these explanations will only constitute a starting point for the discussion of other questions that we will try to answer in this study, because it mainly aims at examining the special cases related to mistake in identity and mistake in the blow. As an example for this, we may mention how the mistake in identity of the perpetrator or his/her mistake in the blow would affect the criminal liability of other persons as far as collective crimes are concerned. Another issue to be addressed is what kind of an impact these two concepts would give rise to as far as crimes committed in the state of self-defense and under unjust provocation is concerned. We will also examine the incidents where the perpetrator has not seen the victim, for example the crimes committed from a definite distance and the consequences of the crime occurs not on the person intended by the perpetrator but another person.