Two teenage girls have been found guilty of murdering a retired Opotiki teacher by beating him to death.

The girls, who are cousins, bashed 78-year-old John Rowe to death with walking sticks as they tried to rob him at his home last November.

Courtney Churchward was 17 at the time and Lori Lee Te Wini was just 14.

The jury returned its verdict at the High Court in Rotorua after almost five hours of deliberations.

Mr Rowe's children Wendy and Patrick Rowe say they are satisfied with the verdicts, but sickened at the age of the two girls. Wendy Rowe says her father was a quiet and independent man who liked living alone and always felt safe in his Opotiki home. She says she will never understand how anyone so young could do such a vicious thing.

Te Wini's name had been suppressed until now due to her age. She may be the youngest female in New Zealand to be convicted of murder. She is 15 now, but was only 14 when she committed the crime.

Jahche Broughton was also 14 when he murdered Scottish tourist Karen Aim in Taupo in January last year. The previous youngest female murderer was Natalie Fenton, who was 15 when she stabbed Raymond Mullins to death in 1999.