The spokesman said that the Crown Office had published the findings of a "landmark review" of the investigation and prosecutionof sexual offences, which he said would give victims "increased confidence" in quality of investigation and prosecution.
The first prosecution under section S72 of the Sexual Offences Act of 2003 involved Barry McCloud, who was jailed for life in 2010 for sex offences against a girl in Goa.
The Crown Prosecution Service said the offences committed carried maximum sentences of 10 years, but the four-year sentences were the lengthiest related to rioting so far.