A Nevada student who gave the opening address at his high school graduation last year has been charged with breaking into his school district's computer system and bumping up his classmates' grades for a fee.

Police say Tyler Coyner, 19, was the ringleader in a group of 13 students who have been charged with conspiracy, theft and computer intrusion in connection with the case. Last year, Coyner somehow obtained a password to the Pahrump Valley High School's grade system and, over the course of two semesters, offered to change grades in return for cash payments, police say.

Nye County Sheriff's Deputy David Boruchowitz declined to say in an interview exactly how Coyner allegedly changed the grades, citing the ongoing investigation.

Coyner boosted the grades of a dozen students but saved the biggest improvements for himself, police said. He was selected as his school's salutatorian at the 2010 graduation, an honor he never legitimately earned, according to the Nye County Sheriff's Office. The salutatorian honor is usually given to the student with the second-highest marks at graduation.

Coyner, now a student at the University of Nevada in Reno, had a 4.54 grade point average, according to a profile of him in the Pahrump Valley Times, written around the time of his graduation last year.

In his address, which is viewable on YouTube, Coyner describes himself as a formerly shy student who was much changed by his high school experience. "I changed for the better, learning what it meant to be a student at PVHS and taking initiative in completing assigned work. ... Well, sort of," he says in the video.

In the Pahrump Valley Times profile, Coyner says he dreamed of attending an Ivy league school like Harvard and that he wanted to become a hedge fund trader.

Police say they found a flat-screen television, allegedly stolen from a local Wal-Mart, and equipment for making fake driver's licenses in Coyner's dorm room, which he shared with Matthew Miller, 19. Miller is also charged in the case.

A third man, Nicholas Ramoser, also 19, has been charged, along with 10 juveniles, police said.

The Nye County Sheriff's Office believes it has arrested everyone whose grades were changed, but it is still investigating the matter, Boruchowitz said. "We're confident that there were others who knew about it," he added.

Coyner could not be reached for comment Friday, and Pahrump Valley High School Principal Max Buffi did not reply to a message seeking comment.

Robert McMillan covers computer security and general technology breaking news for The IDG News Service. Follow Robert on Twitter at @bobmcmillan. Robert's e-mail address is robert_mcmillan@idg.com