Wellington, April 17 NZPA - A jury in a New York state court is expected to decide the fate of Auckland University graduate Blazej Kot next week after closing arguments in his trial for the murder of his wife, a stem cell researcher at Cornell University.

The jury's main task in Tompkins County Court will be weighing the state of mind of the New Zealander, who has admitted to slashing the throat of his wife, Irish-born Caroline Coffey, WICZ TV reported.

In a key testimony this week, a defence psychiatrist portrayed Kot, 25, as severely depressed, psychotic, paranoid and delusional when cutting his wife's throat on a jogging path near the couple's apartment in Ithaca, close to Cornell University.

Prosecutors alleged that Kot never mentioned such a mental state when first arrested, and had actually planned the murder in an attempt to free himself of his marriage.

Under New York law, evidence of extreme emotional disturbance could enable the jury to find Kot guilty of manslaughter, rather than murder.

Kot is accused of killing Dr Coffey and setting fire to their apartment to hide the crime.

Defence psychiatrist Rory Houghtalen said Kot had a personality disorder which was worsened by the rejection of his research paper and anti-malarial chloroquine tablets he took for a trip to Costa Rica for the couple's marriage ceremony in May, the Ithaca Journal reported.

Severely depressed and psychotic, Kot had the paranoid delusion and fear that he was being tested by Dr Coffey and other people he knew, and thought he could end this testing by killing his wife Dr Houghtalen said.

Closing arguments are scheduled for Tuesday (NZ time).