Quite correct. Many Kapos, especially during the initial phase of establishment and construction of a Konzentrationslager, were actually German criminals or political prisoners. The SS chose these individuals to govern the inmates for several reasons, including the obvious communication benefit, general willingness of the Kapo to mete out punishment on another human being and also the benefits of taking into account their prior "skill set" - i.e. criminal experience, which also came in handy when the SS wanted the prisoners monitored closely.
The items shown in the attachments above are both patently fantasy pieces. Common garbage found on fleaBay etc.
If you really want a reproduction example, I suggest study period images beforehand - that way, you will know what to look for. The amount of fantasy and reproduction variants of these armbands and patches is rather vast.