An Alaska teenager carried out a plot to kill her “best friend” after a man she met online offered her $9 million for pictures and photos of her committing murder, according to authorities.

Cynthia Hoffman, 19, was killed June 2 by a gunshot wound to the back of the head in Thunderbird Falls near the Eklutna River, about 27 miles northeast of Anchorage, the Anchorage District Attorney’s Office said in a statement.

Denali Brehmer, 18, was arrested and charged in the murder. The two teens considered each other best friends, according to court charging documents seen by NBC News. Four other teens and the man who solicited the murder were also arrested in the case.

According to the district attorney’s office, Brehmer allegedly planned the murder after a man she met online told her she would be paid millions for evidence of her murdering someone.

Authorities say Darin Schilmiller, 21, of Indiana, created a fake online persona as a millionaire from Kansas named “Tyler” and began a relationship with Brehmer. The two began planning several crimes in exchange for money, including the “rape and murder of someone in Alaska,” according to court documents.

Cynthia Hoffman, 19, was found dead along a river bank near Thunderbird Falls in Alaska on June 4

After being catfished by Schilmiller, Brehmer chose Hoffman as her victim and recruited four friends, Kayden McIntosh, 16, Caleb Leyland, 19, and two other unnamed juveniles, to help her carry out the murder in exchange for “substantial shares of money,” authorities allege.

Brehmer and two of the teens hatched a plan to take Hoffman to Thunderbird Falls under the guise of a hiking trip, and that’s where they bound her hands, feet and mouth with duct tape and shot her in the back of the head. They dumped her body in the Eklunta River, according to court documents.

Brehmer kept her end of the bargain by sending videos and photos to Schilmiller via Snapchat during the crime, authorities said.

After the murder, the teens destroyed some of Hoffman’s personal belongings and texted her family, saying they dropped her off at a nearby park. Police said there is no evidence Hoffman was sexually assaulted.

Under questioning by police, Brehmer confessed to the murder-for-money plot, according to court documents. Police also found text messages Brehmer sent to Schilmiller of her sexually assaulting minors at his behest, which is what initially led them to the Indiana man.

Schilmiller admitted to catfishing Brehmer as well as blackmailing her into sexually assaulting people after the murder. He told authorities that the two had been planning Hoffman’s murder for about three weeks.

Hoffman’s family said the teen was likely picked by Brehmer because of her being a “trusting young adult whose learning disabilities put her at a younger developmental age than her 19 years,” according to The Anchorage Daily News.

“My daughter trusted these people. My daughter just wanted friends,” Timothy Hoffman, the victim’s father told Anchorage Daily News. “Now I have to bury her.”

The six defendants were indicted by an Anchorage grand jury on June 14 for murder in the first degree, conspiracy to commit murder and murder in the second degree, the Alaska Department of Law said. Each count of murder carries a sentence of up to 99 years in prison.

Schilmiller and Brehmer were each indicted on an additional count of solicitation to commit murder.