A driver working for FedEx was arrested and charged Friday in the kidnapping and killing of a 7-year-old girl who had disappeared from her home's driveway in Texas earlier this week, police said.

Athena Strand's body was recovered Friday evening, Wise County Sheriff Lane Akin said at a news conference.

"It hurts our hearts to know that child died," Akin said Friday.

"It's one of the toughest investigations that I've been involved in because it's a child. And anytime there's a child that dies, it just hits you in your heart," he said.

Athena was reported missing Wednesday and authorities launched a search for her across Wise County, located northwest of Fort Worth. Authorities believe the young girl was killed within an hour after her kidnapping from her family's driveway, which is about 200 yards from her home.

Tanner Lynn Horner, 31, is being held in Wise County jail on capital murder and aggravated kidnapping charges, according to its website. Bond was set at $1.5 million, Akin said. It was unclear whether Horner had an attorney Friday.

Horner, identified by authorities as a contract driver for FedEx, was allegedly making a delivery to Athena's home at the time she disappeared.

Earlier Friday, police say they received a tip that helped investigators determine Horner abducted the child from her driveway.

Strand's mother, Maitlyn Presley Gandy, said her daughter was taken from her by "a sick, cruel monster for absolutely no reason," she wrote in a Facebook post on Saturday morning.

"I cannot describe the pain and absolute anger I feel. Missing her doesn't cover how I feel," Gandy said in the post accompanying a video of Athena, then age 3 "I want the world to know my baby, my first baby, my first true love, the reason I breathe."

"Athena is innocent, beautiful, kind, intelligent, and just the brightest, happiest soul you could ever meet. I don't want her to be the girl known as the one murdered and discarded by a monster," she added. "I want everyone to know, every single person in this world, that this is my baby and my baby was taken from me. I want everyone to know her face and her voice and just how wonderful of a person she is."

Athena will be remembered for so much, like her dream of growing up to be a Viking princess with tattoos just like her dad's, how much she loved her two little sisters, and her love for anything pink, her mother wrote.

Authorities did not indicate a possible motive and said Horner did not know the family or the child, according to Akin.

Athena's cause of death remains under investigation and her body was transferred to the medical examiner's office Friday, Akin said.

In a statement to CNN, FedEx expressed its sympathies and directed further questions to law enforcement.

"Words cannot describe our shock and sorrow at the reports surrounding this tragic event. First and foremost, our thoughts are with the family during this most difficult time, and we continue to cooperate fully with the investigating authorities," the statement reads.