LITTLETON, Colo. -- Authorities are finally beginning to release key information to support their claim that Eric Harris and Dylan Klebold massacred 12 students and a teacher at Columbine High School in April largely for the fame.

Wednesday, prosecutors disclosed for the first time the existence of secret videos Harris and Klebold apparently created specifically for police. "It is obvious that these guys wanted to become cult heroes of some kind," Deputy District Attorney Steve Jensen told the Denver Post. "They are making statements which they thought would facilitate that status."

That would confirm lead investigator Kate Battan's conclusion, first published by Salon News in September, that the pair was strongly motivated by the prospect of fame.

Salon News independently confirmed the existence of the videos, as well as investigators' intentions to keep them hidden as long as possible.

Harris and Klebold "certainly wanted the media to write stories about them every day," Battan said during an interview in September. "And they wanted cult followings. They're going to become superstars by getting rid of bad people. And you know, it worked. They're famous."

"So it was really just for fame?" I asked incredulously.

"That's my personal opinion," she replied. "And all the rest of the justifications are just smoke." In separate interviews, other investigators agreed.

At the time, Battan refused to cite specific statements to support her conclusions, but indicated she based them on the famous texts left behind by Eric Harris, interviews with family and friends and "other" undisclosed evidence. Battan has steadfastly refused to speak to the media before or since to expand on the basis for her conclusions.

Existence of the tapes was finally disclosed publicly Wednesday, because they will play a role in Friday's sentencing hearing of Mark Manes, 22. Manes pleaded guilty to two Class 4 felonies for possessing and selling Harris and Klebold the TEC-9 semiautomatic handgun used in the massacre.

Chief Deputy District Attorney Mark Pautler told Salon News that the judge had wide discretion in sentencing, and the state would attempt to demonstrate aggravating factors. According to the statutes, he said, Manes could receive anywhere from one to 24 years in prison. Battan will testify to how many people were killed with the TEC-9, and read a brief passage from one of the videotapes where Manes is mentioned.

Authorities said the videos were a blatant attempt by the killers to gain publicity, so they intend to aggressively fight any attempts to release them.