An arrest has been made in the death of a 10-year-old girl from Thornton. An AMBER Alert was first issued for Kiaya Campbell last Thursday -- hours before her body was found.

Thornton police tweeted Sunday morning that a 15-year-old boy was arrested for the investigation of first-degree murder. Last week, they confirmed Kiaya was last seen walking with the 15-year-old son of her father's girlfriend. However, they aren't confirming that he is one who was arrested because the suspect isn't an adult.

The 15-year-old boy was officially charged with killing a 10-year-old girl on Wednesday. The boy could be tried as an adult.

Adams County District Attorney Dave Young said Wednesday after a closed hearing that the boy was charged with first-degree murder with intent to kill after deliberation, and first-degree murder of a child under 12 by someone in a position of trust.

Young said he intends to prosecute the boy as an adult. Authorities have not released the boy's name.

Kiaya was last seen around 8 p.m. Wednesday when she left her father's home on Forest Drive in Thornton to walk to a nearby shopping center. The 15-year-old she was walking with claimed they were separated during a thunderstorm. Then, Thursday evening, Kiaya's body was found less than two miles from the spot where she was last seen in a residential area near a creek and greenway.

The Thornton community has come together to show their support for Kiaya's family.

"I can't imagine what they are going through, how hard it can be for them to lose someone they love," said nearby resident Stacie Russell.

Police first said the death of Kiaya was not accidental on Friday. The following day, they stated it was being investigated as a homicide. Police said prior to the arrest, a large amount of evidence was in the process of being collected, sorted and analyzed in connection with the young girl's death.

While the details of the homicide are unknown, police say there were signs of severe trauma. Police haven't released any more information on the arrest, including a possible motive.

"Rest in peace," said resident Tiffiny Duvall. "We will figure out what happened, and we will support this family as long as we can."

If anyone has information on this incident, please contact the Thornton Police tip line at 720-977-5069.