An international law expert says a Kenyan man wanted in relation to a Christchurch homicide must be charged with a serious crime to be extradited.
The police say Samuel Njuguna travelled to Kenya after a brutal attack in a Christchurch home left his wife in a coma and a man dead.
Kevin Dawkins, a professor in international law at the University of Otago, says New Zealand does not have an extradition treaty with Kenya and for Mr Njuguna to be extradited, the police would have to lay a serious indictable charge against him.
The police have approached the Kenyan High Commission to help track down Mr Njuguna, and have consulted Crown Law about extradition.
Mike Pflanz, a Nairobi-based Daily Telegraph journalist, says Kenya has an Extradition Commonwealth Countries Act which would give its Attorney-General the right, if asked, to begin the extradition process.
He says the New Zealand police would need to present strong evidence and the man could appeal against the order. The process could take some time, he says, given Kenya's slow judicial system.
Wife moved house after couple separated
Lydiah Munene was found in the bedroom of the Ilam house on Monday evening and is in an induced coma in Christchurch Hospital. Stephen Maina, 38, who moved from Kenya to Ashburton a year ago, was found dead beside her.
Ms Munene moved to the house with her two children about a month ago, after separating from her husband. The couple had lived in New Zealand for many years.
Officers were called to the address at about 6pm on Monday by friends who were worried they had not heard from Ms Munene or Mr Njuguna.
Detective Inspector Greg Williams says the police were called to the house two weeks ago when an argument between the estranged couple became heated, but there was no physical violence and no indication the situation might escalate.
Left country after leaving children with friend
The police say Mr Njuguna dropped the couple's children at a friend's house on Saturday and travelled to Kenya the following day.
The movements of his red Peugeot saloon over the weekend are of interest to the police. Mr Williams says a weapon was probably used in the killing, but he will not say what it was or whether it has been recovered.
