On Thursday, some of those relatives headed to Bulgaria but could not immediately be contacted by phone.
"From the outset, we have said finding Maria's mother is the key to this case. We are not afraid of what she has to say," Katsavos told CNN over coffee at a pavement cafe.
Almost as he spoke, Bulgarian police reported they had questioned a Roma couple in central Bulgaria who claimed they were Maria's biological parents.
DNA tests have now been scheduled before the weekend, police say, to see if they can resolve the mystery of who is Maria and whether she was the victim of child traffickers or simple the daughter of parents trapped by poverty.