The Eyrie

DALLAS, TX — Dallas police are asking for the public’s help in finding 13-year-old Natalie Armstrong, who has been missing since she was last seen leaving a DART train at SMU/Mockingbird Station on Oct. 21. Authorities say she was seen with another person, believed to be a juvenile, before being spotted later on foot the same night.

The Dallas Police Department said Armstrong may need assistance. Her mother, Megan Bernhardt, said the teen left without a phone, money, or electronics and has not contacted her family since she disappeared.

Timeline of Armstrong’s last known movements

Police said Armstrong was seen exiting the train at SMU/Mockingbird Station at about 8:43 p.m. on Oct. 21. A later sighting placed her in the 9300 block of Whistle Stop Place at about 10:08 p.m. that night.

Those are the last known locations released publicly by investigators. Dallas police shared the case on Facebook on Oct. 26 as the disappearance reached the six-day mark, asking anyone with information to come forward. The department has not said where Armstrong went after that point or who the other person may have been.

Mother says the teen left with nothing and has not called home

Bernhardt told NBC 5 DFW that her daughter left with no phone, no money and no electronics. She said the family has had no contact with Armstrong since the night she disappeared, despite the fact that the teen knows her phone number.

Her mother said it is especially alarming that Armstrong has not reached out. Bernhardt said she has been urging parents to ask their teenagers whether they have seen or spoken with her daughter, noting that Armstrong may be more comfortable approaching someone her own age than an adult.

Family says Armstrong has autism and may have walked a long distance

According to Bernhardt, Armstrong is autistic and had been dealing with anxiety tied to school before she went missing. She also said her daughter likes to walk, which is one reason the family believes she may have traveled a considerable distance on foot.

Police described Armstrong as 5-foot-3, about 135 pounds, with brown hair and hazel eyes. She was last seen wearing a black hoodie, blue jeans, and white shoes. The department said she may be in need of assistance, a detail that has shaped the search efforts and public appeals.

Search efforts have focused on possible sightings in Grapevine

Armstrong’s family has been concentrating its search in the Grapevine area after reports of possible sightings, NBC 5 DFW reported. Bernhardt said the family is following leads while trying to keep attention on the teen’s disappearance and possible travel routes.

A volunteer missing persons tracker, Alfonso Solis, also posted a Facebook video urging the public to help. He said Armstrong is familiar with the DART rail system and asked residents to check sheds, common areas, gyms, clubhouses and other places where someone could be overlooked.

How the public can share information with Dallas police

Dallas police are asking anyone who knows where Armstrong may be to call 911 or contact the department at 214-671-4268. Investigators asked people to reference case number 155505-2026 when they call.

Bernhardt spoke directly to her daughter in comments shared by NBC 5 DFW, saying the family loves her and wants her to come home. She said Armstrong is not in trouble and that the family only wants her safe return.

The Dallas Police Department did not immediately respond to PEOPLE’s request for comment.

What investigators have and have not said so far

Police have identified Armstrong’s last public sightings and released her description, but they have not said how she and the other person became separated, whether foul play is suspected, or whether investigators have confirmed any additional sightings. The public appeal suggests officers are treating the case as one in which the teen could need help.

For now, the search remains centered on the timeline from the train station to Whistle Stop Place and on tips from people who may have seen Armstrong after Oct. 21. Police and family members are asking the public to stay alert and report anything that could help locate her.