ABC News is set to air an investigative piece that looks into whether the brutal killing of college student Matthew Shepard was motivated primarily by a combination of crystal meth and robbery--not the fact that he was gay, a network spokesman tells Advocate.com. The death of the 21-year-old Shepard--who was beaten, tied to a fence post, and left to die near Laramie, Wyo., in 1998--sparked outrage and activism by gay rights groups across the country. The killers, Aaron McKinney and Russell A. Henderson, are serving consecutive, double life sentences. "I think we discovered that there were some new facts relating to the case and wanted to explore that," said ABC News spokesman Jeffrey Schneider of the 20/20 report that will air on November 26. The segment will explore Laramie's underground world of meth and whether or not Shepard knew his killers. "I think that mugging and crystal meth are the two possible things that we're exploring," Schneider said. He declined to comment who the piece suggests was on meth. "We saw the press release, and it definitely raised our eyebrows," Glennda Testone, spokeswoman for the Gay and Lesbian Alliance Against Defamation, told Advocate.com. She declined to comment further until the piece has aired. Sirius/OutQ commentator Romaine Patterson, one of Shepard's close friends, told the New York Post, "Does it make Aaron McKinney and Russell A. Henderson any less guilty of the crime they committed? Absolutely not. You just don't kick someone in the crotch over and over again unless you have a real problem with their sexuality. To imply otherwise, in my opinion, is irresponsible, and I think it's irresponsible to be giving a voice to two very guilty men." The interview with McKinney likely violates the plea agreement he signed at his sentencing, according to the newspaper. McKinney agreed never to talk to the media about the case as part of the agreement that spared him the death penalty. Henderson's lawyer, Tim Newcomb, did not return calls by the newspaper seeking comment.