Evelyn Mae Boswell was not reported missing until Feb. 18, authorities say.

A desperate search is underway in Tennessee for a 15-month-old girl who authorities say was last seen in December.

Evelyn Mae Boswell, of Sullivan County, was entered as a missing child on Tuesday, but she was reportedly last seen on Dec. 26, according to the Tennessee Bureau of Investigation.

Investigators with the Sullivan County Sheriff’s Office and the Tennessee Department of Children’s Services immediately launched an investigation, with assistance from the Tennessee Bureau of Investigation and the Federal Bureau of Investigation. A statewide Amber Alert has been issued for the little girl.

Evelyn, who is white and has blonde hair and blue eyes, was last seen wearing a pink tracksuit with pink shoes and a pink bow in her hair. She is about 2-feet tall and weights 28 pounds, according to the Tennessee Bureau of Investigation.

The Sullivan County Sheriff’s Office said the child’s mother, Megan “Maggie” Boswell, has been involved in the investigation along with the father, Ethan Perry, who is active duty in the U.S. military, stationed in Louisiana.

No additional information about her disappearance was immediately released.

Anyone with information regarding Evelyn’s whereabouts is urged to contact the Sullivan County Sheriff’s Office at 423-279-7330 or the Tennessee Bureau of Investigation at 1-800-TBI- FIND.

ABC News’ Ahmad Hemingway contributed to this report.