The defence will open its case tomorrow in the trial of two teenage girls accused of the brutal slaying of a retired Bay of Plenty schoolteacher.

Courtney Churchward, 18, and a 15-year-old girl whose name is suppressed, have pleaded not guilty in the High Court in Rotorua to murdering 78-year-old John Rowe at his Opotiki home on November 25 last year.

The prosecution alleged that the two teens broke into Mr Rowe's house to rob him.

At the time Mr Rowe was recuperating from an ulcerated leg and was due to return to hospital for further treatment the next day.

When the pair arrived at his home they wore socks over their hands. They covered these with latex gloves taken from a box used by Mr Rowe's caregiver to dress his wounds.

They then went into his bedroom and attacked him with a wooden broom handle and a walking stick.

His battered body was found by a neighbour the next morning.

The trial is expected to finish this week.