The defence for the man accused of murdering his partner and hiding her body in a lake says her death was a spontaneous, unscripted event.

Cory Jefferies, 46 is on trial in the High Court in Hamilton, accused of murdering 42-year-old Kim Richmond.

Her body was discovered in Lake Arapuni in June 2017, 10 months after she disappeared.

Mr Jefferies had admitted her manslaughter, but denies murder Ms Richmond.

Defence lawyer Thomas Sutcliffe today described Ms Richmond's death as a spontaneous, unscripted event, with terrible consequences that no one saw coming.

In his closing address before the jury today, defence lawyer Thomas Sutcliffe described Ms Richmond's death as a spontaneous, unscripted event, with terrible consequences that no one saw coming.

Claims by two witnesses that Jefferies had threatened to kill Ms Richmond on more than one occasion were not threats even if their claims were true, said Mr Sutcliffe, as there were emotional outbursts or expressions of frustration over the failure of their relationship.

Mr Sutcliffe said Mr Jefferies' actions after she died - when he pretended she has driven off and left him - were not evil, but more of a cover up to protect his family and their three children in particular.

He said Jefferies' ruse was not well thought-out and while it was effective for some time, it still came unstuck.

Mr Sutcliffe said self-preservation by Mr Jefferies and trying to maintain a terrible lie did not reflect an intent to murder.

He told the jury that the Crown's case was seriously wanting and the evidence did not prove murderous intent beyond reasonable doubt.

Justice Fitzgerald will sum up the trial on tomorrow morning before the jury of seven women and five men retire to reach a verdict.