ThisYouWillDo
I read in Portugal officially naming a person as suspect gives the police additional questioning powers. This may not mean the police suspect the person of commiting the crime, it may simply mean they think the person is withholding information. The article I read suggested the police had reason to think the parents were not being helpful and needed those additional powers in order to try to get the information they wanted.
I would imagine ruling out family and those close to the victim is a step 1 in police procedure given the high percentage of case where the perp knows the victim. People may be reading too much into the naming of the parents as suspects.
This case reminds me very much of the JonBenet case. Unusual circumstances, professional parents, police unsatisfied with the parents cooperation, use of media etc.