In this undated handout image from Mexico’s Attorney General’s Office, Arturo Beltran Leyva is seen.  A Mexican navy official said alleged drug cartel chief Arturo Beltran Leyva was killed in a shootout with sailors Wednesday Dec. 16, 2009. The official says Beltran Leyva and three other suspected members of his cartel were killed in a shootout with sailors at an apartment complex in the city of Cuernavaca, just south of Mexico City.

Beltran Levya, known as the “boss of bosses,” was one of four brothers who split from the Sinaloa cartelLos Zetas several years ago and aligned themselves with , a group of former soldiers hired by the Gulf Cartel as hit men.

That split is believed to have fueled much of the bloodshed across Mexico, where more than 14,000 people have been killed in the past three years.

The U.S. Drug Enforcement Administration says the Beltran Leyva cartel is a key organization in importing and distributing tons of cocaine in the United States, as well as large quantities of heroin.