ANCHORAGE, Alaska (AP) — Alaska teens hoping to cash in on a $9 million offer from a Midwest millionaire brutally killed a developmentally disabled woman on a popular trail outside Anchorage, shooting her in the back of the head and dumping her body in a river, authorities allege.

The millionaire's only demand for the payout was either photos or video of the slaying, according to court documents laying out first-degree murder and other charges against six people in the June 2 death of 19-year-old Cynthia Hoffman.

"This is a truly horrific case that is not the norm for our community," Anchorage Police Chief Justin Doll said at a news conference, the Anchorage Daily News reported .

Among those charged is Darin Schilmiller, whom authorities say presented himself as the millionaire Tyler from Kansas, using a fake photograph. "He does not look like the young man he portrayed himself to look like, he is not a millionaire and he lives in Indiana," court documents say.

Authorities say Schilmiller, who has been arrested in New Salisbury, Indiana, and will be transferred to Alaska next month, began an online relationship with 18-year-old Denali Brehmer of Anchorage, posing as Tyler. About three weeks before Hoffman was killed, Brehmer and Schilmiller began discussing a plan to rape and murder someone in Alaska, according to court documents.

"Schilmiller offered Brehmer nine or more million dollars to carry out the murder and to have photographs and/or videos of the murder sent to him," the documents say. "Brehmer agreed to commit the murder for him."

Brehmer then enlisted the help of four friends, including 19-year-old Caleb Leyland, 16-year-old Kayden McIntosh and two other unnamed juveniles, to plan and carry out the murder at Schilmiller's direction, according to the documents. The group met to decide how they would divvy up the money.

McIntosh, who is being tried as an adult in the case, was the gunman, prosecutors say.

Hoffman was allegedly best friends with Brehmer, and she was chosen by the group as the victim, the documents say.

Brehmer and McIntosh used Leyland's pickup on June 2 to take Hoffman on a hike at Thunderbird Falls, a popular location about 20 miles (32 kilometers) north of Anchorage. According to court papers, the group went off trail and followed a path to the bank of the Eklutna River, where Hoffman was bound, shot and thrown into the river. Officials said there was no indication Hoffman was sexually assaulted.

"Digital evidence and statements show Brehmer was communicating with and sending videos and/or photographs of the events surrounding the incident to Schilmiller at his directive through the duration of the event," documents say.

Officials allege they destroyed some of Hoffman's clothing, purse and cellphone, and Brehmer texted Hoffman's family to let them know they dropped her off at Polar Bear Park in Anchorage.

Two days later, both Brehmer and McIntosh were interviewed. McIntosh was arrested, but Brehmer denied any involvement in the death. Police continued to investigate and interviewed her two days later after Snapchat video appeared, in which she appeared to confess, the documents say.

"Brehmer ultimately admitted to being solicited by Schilmiller to commit the murder and that the murder was planned once she realized she had been catfished by Schilmiller," the documents say. Catfishing is when a person creates a fake identity on a social network account to deceive a specific victim.

Schilmiller admitted to federal agents and Indiana State Police his role in the plot, saying he chose Hoffman as the victim and he told Brehmer to kill her, according to the court documents.

He also told officials Brehmer communicated with him throughout the murder, and sent Snapchat photographs and videos of Hoffman while bound and then after the murder. He also allegedly told authorities that he and Brehmer discussed killing another person, but the plan was abandoned, and he admitted to blackmailing Brehmer into raping people.

In a separate federal investigation rising from the investigation, Schilmiller and Brehmer were indicted Tuesday on federal child pornography charges, including production and coercion and enticement of a minor. Federal authorities allege Brehmer produced sexually explicit videos involving a minor and sent them to Schilmiller.

"For all the good the internet can do, it can be a very dark place," Bryan Schroder, the U.S. attorney in Alaska, said at a news conference Tuesday. "Parents would be wise to monitor the activity of their children online."

The Alaska teens are being represented by the public defender's office, which has a policy of not commenting on cases. Online court records did not list an attorney for Schilmiller.

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Information from: Anchorage Daily News, http://www.adn.com

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