MEXICO CITY -- Bloody bodies -- slumped at steering wheels, stacked in pickup trucks, crumpled on sidewalks -- clog nearly every frame of the music video that shook Mexico's criminal underworld.

Posted on YouTube and countless Mexican Web sites last year, the video opens with blaring horns and accordions. Valentín Elizalde, a singer known as the "Golden Rooster," croons over images of an open-mouthed shooting victim. "I'm singing this song to all my enemies," he belts out.

Elizalde's narcocorrido, or drug trafficker's ballad, sparked what is believed to be an unprecedented cyberspace drug war. Chat rooms filled with accusations that he was promoting the Sinaloa cartel and mocking its rival, the Gulf cartel. Drug lords flooded the Internet with images of beheadings, execution-style shootings and torture.

Within months, Elizalde was dead, shot 20 times after a November concert. His enemies exacted their final revenge by posting a video of his autopsy, the camera panning from Elizalde's personalized cowboy boots to his bloodied naked body.

Elizalde's narco-ballad video and its aftermath highlight a new surge of Internet activity by Mexican drug cartels, whose mastery of technology gives them a huge advantage over law enforcement agencies. Following the model of terrorist groups such as al-Qaeda, the cartels have discovered the Web as a powerful means of transmitting threats, recruiting members and glorifying the narco-trafficker lifestyle of big money, big guns and big thrills.

"It's out of control," Victor Clark, a Tijuana-based drug expert, said in an interview.

Drug raids in Mexico now routinely net cameras, computers and intricate computerized surveillance systems along with the usual piles of cash, cocaine and weapons. Hit men are just as likely to pack video cameras as "goat's horns" -- the Mexican drug world's nickname for AK-47 assault rifles.

Mexican police have been slow to recognize the Internet as a font of clues, critics say, a mistake that has increased the ability of the cartels to work in the open.

"Imagine, if you're a policeman, you can find gold here on these Web sites," said Alejandro Páez Varela, an editor at the Mexican magazine Dia Siete who tracks drug gangs' use of the Internet. "It's a shame. Everything's here: names, places. They even say who they are going to kill."

The videos, almost unheard-of a year ago, now show up with disturbing regularity. Last Monday, Mexican newspaper Web sites published portions of a video of a supposed Gulf cartel hit man being questioned by an off-screen interrogator about the February murders of five police officers in Acapulco.

The man wears nothing but underwear. A large "Z" is scrawled in thick ink on his chest, along with the words "Welcome, killers of women and children." The Z is a symbol of the Zetas, the Gulf cartel's notorious hit squad, which was started by former Mexican army special forces officers.

The full version of the video shows assassins decapitating the man by slowing twisting a wire through his neck. It ends with a written threat: "Lazcano, you're next" -- an apparent reference to Heriberto Lazcano, alleged chief of the Zetas.