In Ciudad Juarez, across the Rio Grande from El Paso, Texas, killings are down 35 percent in 2011, McClatchy Newspapers reported. Recently, there was a period of almost three days with no homicides.
Instead, bodies are turning up in Guadalajara and Veracruz. Last week, 26 bodies were left in three vehicles under the Millennium Arches in Guadalajara.
"Look how we leave you these dead people," a poster signed Z for Los Zetas, said. "We are in your kitchen."
Members of the Sinaloa cartel have been involved for 50 years in smuggling drugs north from Mexico, and the gang, centered on Mexico's Pacific coast, has branched out as far away as Australia.
The Zetas were formed recently. Originally, they were a group of former military commandos who became a militia to protect the Gulf cartel, but they have struck out on their own.
To add to the bloodshed, the Sinaloa group recently formed its own strike force, the Metazetas or killers of Zetas.