A person has been arrested for kidnapping Yanfei Bao, but there is still no news on where the missing real estate agent from New Zealand is.
Stuff understands the man was arrested at an airport.
Police said he had been remanded in custody and was due to appear in the Christchurch District Court on Monday.
"The investigation is ongoing, and several people are assisting police with inquiries," Detective Inspector Nicola Reeves said in a statement.
As part of those inquiries, police were seeking sightings of a silver Mitsubishi sedan, registration DPH101.
"We're interested in sightings of the vehicle from mid-week up until last night, but with a particular focus on the vehicle's location on Wednesday 19 July in Wigram, Hornby, Tai Tapu, Halswell, Redcliffs, and New Brighton," Reeves said.
Bao's sister, Huafei, said the family suspected the kidnapping was in relation to a cash buyer who was looking to get $600,000 ($550,949) from China to purchase a property.
From conversations with her sister, Huafei believed money had been tight for Bao.
Huafei was hopeful after hearing that Bao had been kidnapped.
"The thing I hope for most is to find my younger sister, and that she is OK," Huafei sobbed as she spoke to Stuff.
She said she had not slept and was feeling numb as she waited for news of her sister.
Meanwhile, police continue to investigate a house linked to Bao's disappearance in suburban Christchurch.
In a development overnight, police confirmed they had seized a vehicle of interest in relation to the investigation, and had searched two properties, one in Bryndwr and one in Wigram.
Several people were assisting officers, police said.
The large bungalow at Iriquois Place in Wigram is down a driveway. It has a garden shed out front.
A resident earlier told Stuff they had seen Bao's car parked in the street on Tuesday afternoon, a day before Bao disappeared. He said he saw the same car on Wednesday morning parked in a similar place.
He believed he had seen a grey coat rolled up in the passenger seat.
On Sunday morning, a resident, who didn't want to be named, said he had only seen the people in the Iriquois Place house police were looking at a few times.
He said they said hello in a foreign language, and he thought the house was a flat people ran some businesses out of.
Previously, Stuff reported Bao spoke to a friend 45 minutes after she was last seen.
REINZ chief executive Jen Baird said real estate companies took the safety of their staff "very seriously".
"I am sure this situation will sharpen that focus. Everyone in the real estate industry has Yanfei's family, friends and colleagues in their thoughts and we are hoping and praying that she is found safe and well."
At 11.16am on Wednesday, Bao rang her friend Jin Tian and had a four-minute conversation with her.
During the conversation, Bao asked Tian how someone she was working with could transfer the money from China to pay cash for a house.
Tian told The Press, in an exclusive interview, the conversation was in Mandarin and Bao sounded normal with nothing to indicate anything was wrong.
Bao had been going door to door for work at 10.30am on Vickerys Rd when she went missing in the Wigram suburb on Wednesday.
Detective Inspector Nicola Reeves said on Friday that one of her phones was found several kilometres west on the southern motorway near Blakes Rd.
At a press conference on Friday, Reeves said police were "growing increasingly concerned" for Bao and were treating her disappearance as unexplained.
Police had received 40 tips from the public, and were assessing the information.
Bao's distraught family, speaking from China, said they were heartbroken.
Bao's sister, Huafei Bao said: "My mum has been crying since, and passed out a couple of times and my dad is heartbroken. We are just ordinary people. What can we do? We are so far away."
Police contacted Huafei on Saturday night to ask for Bao's ex-husband's details in China, but have not received any further updates on Sunday morning.
Anyone with information that could help police's investigation is asked to report it.
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