TENNESSEE- Authorities in Tennessee have arrested the teenage mother of a missing 15-month-old girl on a false reporting charge. 

Megan "Maggie" Boswell, 18, was taken into custody on Tuesday night and charged with one count of false reports. The Sullivan County Sheriff's Office says Boswell gave investigators inaccurate information amid the desperate search for her daughter, Evelyn Mae Boswell, who was declared missing last week but reportedly last seen by family members in December.

Boswell, who has full custody of Evelyn, told detectives "a number of conflicting statements," the sheriff's office says. 

"Every time we talk to her, her story changes," Sullivan County Sheriff Jeff Cassidy told reporters in a news conference Wednesday afternoon. "And I'm serious when I say that. Every single time." 

The false statements have delayed and impeded the investigation, Cassidy added.

The mother is being held in the Sullivan County Jail on a $25,000 bond. It is unclear whether she has obtained a lawyer.

Evelyn's father, Ethan Perry, who is on active duty in the U.S. military, stationed in another state, has been cooperating with police.

Evelyn became the subject of a statewide Amber Alert issued on Feb. 19. The sheriff's office continues to work alongside the Tennessee Bureau of Investigation and the FBI to find her. Investigators have received over 500 tips, but none have produced any credible sightings regarding the toddler's whereabouts thus far. 

The Tennessee Bureau of Investigation reports Dec. 26 as the date Evelyn was last seen, however, her mother, along with others connected to the little girl, have given conflicting dates. Jeff Cassidy said he is considering the date Evelyn was last seen based on when a babysitter last saw her, which is Dec. 10 or 11.

It is unknown why it took so long to report the child missing. Authorities have followed up on over 500 tips and are currently treating the investigation as if Evelyn is still alive, Cassidy said.