An Arizona teenager who had been missing since 2019 stopped by a Montana police department alone on Sunday and identified herself, sparking questions about her disappearance and recent life that are still swirling days after police announced the news.

Alivia Navarro, now 18, vanished from Glendale, Arizona, in September 2019. Since coming forward about a week ago, she has spoken remotely with her family, who are in Arizona.

Detectives from Glendale executed a search warrant Wednesday and detained a man who has since been released, in Havre, Montana. Police have not released the identify of the man and have not made any arrests in the case.

Glendale police spokesperson Gina Winn said authorities are working to determine what happened over the past four years and whether a crime occurred. Kidnapping is a possibility, authorities said.

Who is Alicia Navarro?

Navarro vanished from her native home of Glendale, Arizona, on Sept. 15, 2019.

A week before Alicia’s 15th birthday, she left her mother a handwritten note in her bedroom saying she would come back home, according to The Arizona Republic, part of the USA TODAY Network.

Video footage of an interview Navarro gave with police this week shows the teenager appearing tired but otherwise healthy.

Jessica Nuñez, Navarro's mother, told the Republic she suspected Alicia may have been abducted by someone she met while online gaming. She had spent most of her time gaming, a hobby she had taken up at 11 years old.

In the years since her daughter's disappearance, Nuñez has partnered with private investigative agencies, put up billboards, appeared on television programs and used social media to find her.

What's the latest in the investigation into Navarro's disappearance?

Reports from the Associated Press suggest Navarro has been seen around the residence that police searched in Montana.

As many as 10 uniformed and undercover officers showed up around 8 p.m. Wednesday and took away a man who appeared to be living there in handcuffs, according to a witness account. The man was questioned and released.

Three other people in Havre have been questioned, Glendale police spokesperson Gina Winn said. She declined to name the people who were interviewed and would not specify whether detectives are still in the Montana town.

Where was Alicia Navarro found?

On July 23, Navarro showed up at a police station in Havre, Montana, about 1,400 miles from where she disappeared from four years earlier. She identified herself and police in Glendale, Arizona, were notified.

After Glendale police received word the young woman had identified herself as Navarro, they went to work on verifying her identity through interviews and with help from the Navarro family.

The town of Havre is in northern Montana, about 35 miles south of the border with Canada. Havre is the county seat of Hill County, Montana, and has a population of about 9,300.

What have police found out about Alicia Navarro so far?

Navarro was found safe, healthy and happy, Glendale Police Department information officer Jose Santiago said at a news conference.

Police in Havre and private investigator Trent Steele said when Navarro walked into the city's police department, she also talked about wanting to move forward in life as an adult, including getting a driver's license.

Police have said Navarro told them she hadn’t been harmed, wasn’t being held, and could come and go as she pleased. She does not face any criminal charges, they added.

Police have emphasized their efforts to afford privacy to Navarro even as investigations move forward.

“She is an adult, so it’s up to her whether or not she wants to go home,” Winn said.

In brief video clips that Glendale police released shortly after she arrived at the Havre police station, Navarro thanked authorities for offering to help her and said: “No one hurt me."

Search for Alicia Navarro spanned years

For years, Nuñez had documented her efforts to find her daughter on a Facebook page titled “Finding Alicia” and an audio podcast. In an emotional video posted Wednesday, Nuñez said "For everyone who has missing loved ones, I want you to use this case as an example. Miracles do exist. Never lose hope and always fight.”

Nuñez had amassed a loyal following on social media throughout the years while sharing inspirational quotes, photos of Navarro as a young child and posts addressed directly to her daughter.

“Alicia I know you will fulfill what you promised,” Nuñez wrote in one post. “You will be back.”

For the past several years, Glendale police followed up on thousands of leads, the department said.  

It was also the first time Arizona issued a Silver Alert for someone who was not an elderly person with dementia, the Republic reported. 

Contributing: Associated Press