SEOUL, South Korea — South Korean police say they believe a possible relative of two children whose bodies were found in suitcases in New Zealand last week is likely in South Korea.

Immigration records show that the unidentified woman in her 40s arrived in South Korea in 2018, but there has been no record of her departure since, said Park Seung-hoon, an official at the National Police Agency in Seoul.

Park said South Korean police have conveyed the information to New Zealand police after receiving a request for investigative help. But South Korean police currently have no authority to track down the woman’s whereabouts or detain her as she remains a New Zealand citizen possibly linked to a crime that had happened in New Zealand, Park said.

It would be difficult for South Korean police to pursue her unless New Zealand officially requests for her extradition, which may happen if the investigation proceeds to a point where Interpol places a red notice against her, Park said.

The woman was born in South Korea and later moved to New Zealand where she gained citizenship. New Zealand police suspect the woman could be the mother of the children found dead, as her past address in New Zealand was registered to a storage unit where the suitcases were kept for years, according to Park.

The remains of the children were found last week in suitcases a New Zealand family purchased from an online auction that involved abandoned goods. The children were between 5 and 10 years old and had been dead for a number of years, and the suitcases had been kept in storage for at least three or four years, Detective Inspector Tofilau Faamanuia Vaaelua said.