Haunting last picture of missing teen Alison Jillian Chao, 15, riding her bike to relative's home before vanishing

A haunting photo of a straight-A student riding her bike to her aunt's house is the last time the teen was seen before vanishing - as her family is desperate to keep the public involved in the case. 

Alison Jillian Chao, 15, was last seen on Tuesday on surveillance footage riding her GT mountain bike from her father's house in Monterey Park, California, to her aunt's in San Gabriel around 5:32pm, according to ABC 7. 

The journey was only four miles, but the young girl never arrived, her family told KTLA. 

'The more time that goes on, the scarier it gets,' her mother, Annie Chao, told the outlet. 'I’m afraid the public will lose interest, and it will be harder to find her. There’s less evidence.

Alison Jillian Chao, 15, was last seen on Tuesday on surveillance footage riding her GT mountain bike from her father's house in Monterey Park, California , to her aunt's in San Gabriel around 5:32pm

Chao is around five-foot-two, weighs 96 pounds, and has black hair and brown eyes

'I haven’t slept in days, and it’s just every parent's worst nightmare.' 

Chao is around five-foot-two, weighs 96 pounds, and has black hair and brown eyes. 

She was last seen wearing a purple t-shirt with black shorts and dark shoes. She was also carrying a backpack. 

Chao has not contacted anyone or posted on social media since her disappearance.  

The family has been hanging flyers around Monterey Park in hopes that someone will recognize the Mark Keppel High School student. 

She was last seen wearing a purple t-shirt with black shorts and dark shoes. She was also carrying a backpack. Chao has not contacted anyone or posted on social media since her disappearance

The Monterey Park Police Department Investigations Bureau is investigating Chao's disappearance (Pictured: Chao as a baby)

'It's been very chaotic,' Annie told ABC 7. 'It sounds crazy but, we don't have a play-by-play for this kind of stuff. What do you do? As a parent, you're making flyers, you're contacting the news, we were out driving around to anyone that was open, posting up flyers. We reached out to the community. 

'The community has really come together to help me look for my little girl.' 

Annie recalled a McDonald's worker who called off work and drove about the city at 1am after the story 'hit home' for him. 

'He drove around at one in the morning looking for her with me,' Annie said through tears.  

'I haven’t slept in days, and it’s just every parent's worst nightmare,' her mother, Annie Chao, said. 'The more time that goes on, the scarier it gets' 

The family has been hanging flyers around Monterey Park in hopes that someone will recognize the Mark Keppel High School student

The mother said her her daughter was bubbly and upbeat and had a lot of energy, according to NBC Los Angeles. 

The Monterey Park Police Department Investigations Bureau is investigating Chao's disappearance. 

DailyMail.com has contacted Annie for comment.