Gannon Stauch
El Paso County Sheriff's Office

Gannon Stauch, who was reported missing from his home in Colorado Springs in January, was pronounced dead Monday at a news conference held by El Paso County Sheriff Bill Elder.

Authorities arrested the boy's stepmother, Leticia Stauch, Monday morning in Myrtle Beach, South Carolina five weeks after she reported her stepson missing. Leticia was charged with murder in the first degree of a child under 12 years of age by a person in a position of trust; child abuse resulting in death; tampering with a deceased human body; tampering with physical evidence.

She is being held without bond and is awaiting extradition hearings before being transported to the El Paso County Jail.

Gannon was reported missing on January 27 after Letecia called 911 and told police he hadn't returned home from a friend's house.

Major Crime Detectives took responsibility over the case the next day and worked hand-in-hand with multiple partners. The case was upgraded from runaway to missing/endangered by January 30.

Authorities said the boy's need for medication combined with the length of time he's been missing and the impending weather caused them to consider him an endangered missing child.

Investigators with El Paso's County Sherrif's Office scanned a neighbor's video surveillance for clues on Gannon's whereabouts. Roderrick Drayton, his neighbor, told KDVR he spent time looking through his surveillance cameras, saying he "couldn't sleep."

Drayton showed a particular video to Gannon's father and reported it to the investigators. Authorities initially declined to share information about the video due to concerns it would compromise the case.

"Please understand, we wanted that kept ... because it is a big part of our investigation. And to share it immediately, we hope will not be detrimental, we hope it will not jeopardize the investigation," Sgt. Deborah Mynatt said.

ABC News obtained the video where it shows footage of the child getting into his stepmother's truck and leaving with her on the day he disappeared. The video also showed Leticia returning home without her stepson.

Drayton said he saw Gannon entering the red pickup truck at 10:13 Monday morning, and saw the truck returning to the house at 2:19 pm without Gannon.

It was reported the boy did not attend class on Monday.

Landen Hiott, Gannon's biological mother, described the news as "a nightmare." She also said she "never thought I'd be standing here" during a press conference hours after the arrest.

Hiott vowed to do everything in her power to bring justice to her boy. She also thanked the thousands of people who helped in the case.

"Gannon is with us. After the stories from people all over the world, he's not only my hero now, he's the world's hero. I thank the community for the positive support from a state I had never visited other than two or three times. I'm astounded by the amount of love."

Authorities are continuing efforts to bring Gannon home to his family so he "can have a proper burial" and give his family "closure."

El Paso County Sheriff's Office is asking anyone with credible information to contact their tipline 719-520-6666. Tips can also be sent via email to shrtips@elpasoco.com.

Gannon is about 4 feet 9 inches tall and weighs 90 pounds. He has brown hair and brown eyes and was wearing a blue jacket with a hood, jeans and tennis shoes when he went missing.