Philip Polkinghorne's relationship with his wife has been a key theme on the first day of his murder trial.

The Auckland eye surgeon has accused of killing Pauline Hanna in their Remuera home in 2021, but his defence claims she took her own life.

Lawyer Ron Mansfield says the couple had an open and loving relationship.

Chelsea Daniels has been in court.

She says the prosecution has laid out its theory on events before Hanna's death.

"The Crown alleges a struggle took place, given Hanna had injuries to her nose, scalp - and bruises on her arm, marks on the left side of her back. Polkinghorne had a fresh cut on his forehead that he couldn't explain."

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