Kobayashi was seen in surveillance video around a downtown Los Angeles Metro train station with an unknown person on November 11, her family said.
"We try not to think the worst. We're trying to keep hope alive, but it has now been basically a week and a day since November 11, when she was last spotted with this unknown person and didn't seem to be OK.
"So, our mind is now going to, you know, abduction and, I hate to say the word, but, you know, trafficked," Larie Pidgeon, Kobayashi's aunt, told CNN's Kate Bolduan on Tuesday.
"We're doing the best that we can, but the family at this point is having to come to the reality that those things could be a possibility," Pidgeon said.
The FBI is assisting the LAPD in the investigation, the field office said in an email to CNN on Monday.
Kobayashi was traveling from Maui, Hawaii, to New York and had a connecting flight at Los Angeles International Airport, her sister, Sydni Kobayashi, told CNN by phone Monday. She had the same itinerary as an ex-boyfriend and the pair decided to keep their flights since they couldn't get a refund but would be going their separate ways once they landed at John F. Kennedy International Airport.
Kobayashi was going to spend time in upstate New York with her aunt, her sister said. But November 11 was the last day anyone heard from her.
Text messages from Kobayashi in the lead-up to her disappearance did not sound like her. She used words like "hun," "love" and "babe," her sister said.
"I personally don't think that was my sister," Sydni Kobayashi said. "She doesn't use the word 'hun.' 'Love' and 'babe,' but never 'hun.' Even her close friends have said the same."
The timeline
On Friday, November 8, Hannah Kobayashi took a flight from Maui to Los Angeles. CNN has obtained a photo that appears to show her getting off the flight at the Los Angeles airport. She did not board her scheduled flight to New York that night, her sister told CNN. Her ex-boyfriend, however, took that connecting flight.
The next day, Kobayashi was spotted at a Taschen bookstore at a shopping center called The Grove in Los Angeles, her sister said, and her family doesn't know why. She then sent a Venmo payment to two people whose names the family does not recognize, Sydni Kobayashi said.
A video was posted on YouTube On Sunday, November 10, showing Kobayashi at the LeBron XXII Trial Experience, an event held at the Nike store in the same shopping center. A photo of the event was also posted on her Instagram account, her sister said.
On November 11 - the last day anyone heard from the missing woman - her mother texted her, asking whether she made it to New York. Kobayashi responded no, her sister said. She also sent messages to a friend saying she didn't feel safe, and that someone was trying to steal her identify and funds, according to screenshots her sister sent to CNN.
"Deep Hackers wiped my identity, stole all of my funds, & have had me on a mind f**k since Friday," one message to a friend said.
Another message said, "I got tricked pretty much into giving away all my funds," followed by one saying, "For someone I thought I loved."
On Friday, the Los Angeles Police Department missing persons unit made a poster about Kobayashi's disappearance, saying she was last seen at the airport. It said she has freckles on her face and a tattoo on her forearm.
CNN has reached out to the LAPD for more information.
On Sunday, in a statement posted to Facebook, Sydni Kobayashi said the family had obtained surveillance footage showing her sister around the downtown Metro train station near Crypto.com Arena, although it was unclear exactly when that footage was taken.
In the footage, Kobayashi is not alone and "does not appear to be in good condition," the family wrote on Facebook, saying they are unable to share further details.
Pidgeon had message for her niece or anyone who may be with her.
"Hannah, we love you. We are all here. Your mom's here, your sister's here, your father's here. The entire world is looking for you," she said.
"If someone has Hannah, I want you to know that she is the kindest, most beautiful soul in the entire world. And please don't hurt her.
"Please just give us back to her. No questions asked. Just don't hurt her. Please."
The video in the player above is from a previous report.
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