Hard evidence is required in Spain, too. The penal process can be initiated in different ways here. Either via a state body, El Ministerio Fiscal (equivalent to the State Prosecutor's Office), or via the various police forces. Alternatively, an injured party can directly 'denounce' a crime. However it reaches the court, the case is then reviewed by a judge or judges. If it's decided there is a case to answer, the court process plays out. If not, it ends there. This is obviously done on the basis of said evidence or lack thereof. If the police, in this case, were to approach Court 9 and present simply a hypothesis without any kind of evidence, it wouldn't get very far IMO.
But since the investigative process is done at both the pre-court stage AND at the in-court stage (just using these prefix descriptions as a way to explain my perspective on this), then I would think that a regular court (versus the women's specialized court) might transfer a case with what they perceive to belong more to the investigative jurisdiction of the specialized court given certain background of the case. It would be helpful to have a link to some standards that are used by the regular courts as to what criteria they would use in order to make this transfer to a women's specialized court. It would seem to me that the regular court could make this determination to transfer early on in their investigation without necessarily having the evidence to justify it, but rather based on the demographics of the case (woman, married, disappeared, husband in Serbia, couple going through divorce, family desribing it as acrimonious divorce, etc.).
JMO, but given the difference in how investigations work in the U.S. with investigations taking place before a case can get to court, and the fact that in Spain investigations occur both before and during the court process, then I think it is reasonable to suggest that the transfer to the specialized court may be pro forma based on certain demographic and background issues.