A top leader of Mexico's feared Zetas drug gang was among 14 cartel members indicted in the United States for money laundering after a raid Tuesday which nabbed his brother, officials said.

The 25-page indictment alleges that Miguel Angel Trevino Morales -- who is believed to be in Mexico operating as the cartel's second in command -- and his brothers hid millions of dollars of drug proceeds in a horse racing and breeding operation.

One of the brothers, Jose Trevino Morales, and his wife Zulema Trevino were among seven people arrested in a massive raid Tuesday which also saw the seizure of prize-winning horses.

"This case is a prime example of the ability of Mexican drug cartels to establish footholds in legitimate US industries and highlights the serious threat money laundering causes to our financial system," said Richard Weber, chief of the Internal Revenue Service's criminal investigation.

"This attack on one of the Zetas' most profitable money laundering schemes is an essential front in the war on drugs and will financially disrupt and help dismantle this violent international criminal organization."

The quarter horse racing front appears to be more than simply a shell corporation. Several of the horses have won major races, including Mr. Piloto, a $1 million All American Futurity winner at Ruidoso Downs on Labor Day 2010.

Nor were the accused making major efforts to stay under the radar -- some of the horses ran with names like Number One Cartel and Corona Coronita Cartel.

The indictment alleges that the scheme began with the purchase of a single horse named Tempting Dash in December 2008. It describes the purchases of dozens more and seeks the forfeiture of "numerous" horses, ranches in Oklahoma and Texas and a slew of equipment.

From selling stolen oil to the United States, trafficking drugs through Central America or killing migrants in Mexico, the Zetas have become one of Mexico's most notorious drug gangs.

The Zetas are believed to have come into existence in the 1990s, founded by deserters from the Mexican special forces hired as hitmen for the powerful Gulf cartel, by then boss Osiel Cardenas Guillen.

Their name comes from the word "zeta" -- Spanish for the letter z -- a code term used by top army commanders.

The original group trained new members -- including rogue soldiers from the Kabiles, a feared special forces branch of the Guatemalan military -- and became known for its ruthlessness, particularly for beheading their victims.

They split from the Gulf cartel in recent years, after Cardenas Guillen was jailed in the United States, sparking bloody Mexican turf wars as they set up their own trafficking operations.

Oscar Omar Trevino Morales, another brother of Miguel Angel Trevino Morales, was named in the indictment. He too is believed to be in Mexico.