The Court of Criminal Appeal has been asked to increase the sentence of a teenager convicted of murdering Callington nurse Pirjo Kemppainen.

The teenager, who cannot be identified, admitted committing the September 2010 murder of the woman, who died from wounds inflicted in a callous attack with weapons including a knife and a large brick.

He was sentenced to 25 years in prison with a non-parole period of 15 years.

The Director of Public Prosecution Adam Kimber, QC, asked the court to increase the sentence because of a change in circumstances