Scientific developments have helped police make an arrest over an indecent assault on a young girl - but they are staying quiet on exactly what those developments are.

A 35-year-old Hamilton man will appear in court next week over an attack on a five year-old girl at Cooks Beach in January last year.

Police say while it has taken time, detailed investigative work and findings from scientific analysis have led to the arrest.

However they don't want to share what the new forensic developments which helped are, because they don't want offenders to know.