When we are tasked to carry out criminal investigations, the circumstances always tend to be very delicate.
An example would be in a case of a parental kidnapping, where the parent fears that the police may not take it seriously and be liable accepting bribes from the other party; or that the courts may not issue warrants in time (they will not do so on weekends), or may simply be trying to extort too much money from both sides.
In the case of a non-parental kidnapping, the client may feel like they have more manoeuvrability and use of more resources by letting us handle the safe return of victim.