Surely arguido status can be removed at any time if evidence is obtained which justifies it?
Apparently not, John. If you're made an arguido, your status as such remains for the duration of the case (unless it's shelved).
2000 CPP:
Artigo 57.o Qualidade de arguido1 - Assume a qualidade de arguido todo aquele contra quem for deduzida acusação ou requerida instrução num processo penal.
2 - A qualidade de arguido conserva-se durante todo o decurso do processo.3 - É correspondentemente aplicável o disposto nos n.os 2, 3 e 4 do artigo seguinte.
http://paulosantos-adv.planetaclix.pt/CPP.htm2000 CPP:
Article 57 Status of defendant
1 - Assumes the status of every defendant against whom indictment is required or statement in criminal proceedings.
2 - The status of defendant is conserved throughout the course of the proceedings.
3 - And correspondingly applicable paragraphs 2, 3 and 4 in the following article.