The New Zealand embassy in Thailand has requested the results of test on two young women who are seriously ill in hospital with food poisoning.
Sarah Carter, 23, died on Sunday after eating at a market in Chiang Mai in the north of the country.
Her friend Amanda Eliason, 24, has had to undergo emergency heart surgery while another companion Emma Langlands, 23, is also still having medical treatment.
Ms Eliason's mother Kay says doctors have taken blood samples but still do not know what caused the trio's sudden illness.
She says it could be up to a fortnight before the two surviving women are able to return home.