Mexico says it has arrested a senior leader in the Zetas drug cartel, potentially dealing a major blow to one of the country's most powerful and violent drug gangs. "A person who is presumed to be and who says he is Ivan Velazquez Caballero, aka "Z-50"... one of the main leaders of the Zetas cartel, has been captured in San Luis Potosi state" in northern Mexico, the navy said in a brief statement late Wednesday. It said it would provide more information about the arrest on Thursday. Velazquez Caballero was on a list of Mexico's most wanted drug traffickers, with an offer of some $2.3 million for information leading to his capture. Much of northern and eastern Mexico is in the clutches of the Zetas cartel, which was founded by former Mexican special forces soldiers who went rogue and are known for decapitating and dismembering their enemies. The Zetas were originally hired as enforcers for the Gulf Cartel, but turned on their employers and have taken over their lucrative turf, which includes key land routes to smuggle drugs across Central America and into the United States. Mexico has been in the grip of a massive crime wave in recent years, with some 60,000 people reportedly killed in drug-related violence since the launch of a military crackdown against the cartels in 2006.