16-year-old left Missouri home weeks ago. Her dad is worried she's in danger.

It's not the first time that Timmy Treon's daughter has run away, but as the days turn into weeks, his fears grow that the Missouri teen is in serious danger.

Taking a car that was her 16th birthday gift, Jaiden Treon left her home in the St. Louis suburb of Festus on June 22, Treon told USA TODAY on Wednesday.

He said he now believes the teen is on foot and doesn't know anything about how she's getting by.

"We feel strongly someone's going to take advantage of her," Treon said.

That's why he's been relentlessly pressing Missouri law enforcement to make her case a priority. As far as he's concerned, they haven't.

Missing sisters:Teen sisters have been missing from Michigan since June. The FBI is joining the search.

Unexplained delay

On Wednesday, nearly two months after Jaiden left her home, the Jefferson County Sheriff's Office shared an alert about the missing girl for the first time in a post on Facebook.

The brief post said that Jaiden may be in St. Charles or St. Louis counties, the city of St. Louis or in the state of Illinois. It directs people to call police with any information about her whereabouts.

The sheriff's office did not immediately respond to a request from USA TODAY on Wednesday about why the case hasn't been publicized sooner.

Several people posed that question on the Facebook post, including Treon. The sheriff's office responded to one of them that a detective has been following leads since the case was reported but did not say why the alert wasn't issued sooner.

Treon told USA TODAY he has "no idea" why weeks passed before the sheriff's office publicized the case but wonders if's because they consider his daughter "a habitual runaway."

"They seem to not want to invest much time into a lost cause," Treon said.

A father's fight

Meanwhile Treon has been posting information about his daughter on Facebook since she went missing, and asking members of the public to share it far and wide.

"She has no identification, only the clothes on her back, staying wherever with whomever," he wrote on July 31. "Somebody somewhere is going to be the HERO that finds her. Maybe that is YOU - please help us."

Jaiden is described as being white with black hair and hazel eyes.

Anyone with information about the girl's whereabouts can call the sheriff's office at 636-797-9999.

Juvenile shooting:Juvenile detained in North Carolina shooting death of 8-year-old girl

Eric Lagatta covers breaking and trending news for USA TODAY. Reach him at elagatta@gannett.com.