Under Dutch law a suspect pretty much has the right to say anything he wants or nothing at all for that matter, provided that a confession or statement should not be coerced from the suspect.
Aruban criminal law however, although largely based on Dutch law, has some significant differences, some of which are specifically targeted on their geographic, insular situation and the fact that the appeal procedures are interwoven with courts of law in the Netherlands Antilles (Appeal Court) and the Netherlands (High Court appeal).
SInce Aruban, Antillean and Dutch law do not use a jury system, a initial plea of guilty or not guilty is less significant than it is for instance in US or English/Welsh law. It is up to the prosecutor to build a case from all the facts and statements (the 'dossier') and present a plausible suspicion of guilt on the part of the defendant on which, in the case of serious crime, a panel of three judges may rule.
Although varying one's statements may appear confusing, it is generally considered a poor defensive strategy as it degrades the credibility of the defendant and puts him in a position where he has to account for the many discrepancies that creep in from one statement to the next. In the end, it's the prosecutor who puzzles together the pieces and draws his conclusions, not the defendant.
In spite of a few spectacular events surrounding the tragic Holloway case, the investigation doesn't seem to produce enough hard evidence to hold up in court. At some point, the Aruban authorities requested the help of Dutch police investigators but IMHO that was a rather late decision and the only thing these investigatorscould do was go over the evidence again, but were unable to uncover any new facts at that stage.
Netherlands Prosecution Service