HOUSTON -

The discovery of 49 mutilated bodies has brought the bloody battle between two Mexican drug cartels back into the headlines.

It's a war that has shown it's ugly face here in Houston at times.

The mass grave on the highway leading into San Juan is just the latest swing in a gruesome fight after a fierce six-year war between law enforcement and the drug cartels.

The Zetas and the Sinaloa have been left battling over drug routes and territories near the United States border.

The 43 men and six women found dead at dawn on Sunday are just the latest victims in the most recent burst of violence.

In the last 30 days, in the city of Nuevo, the dismembered and mutilated bodies of 14 men were found stuffed in two abandoned vans. Another 23 people were found hanged.

Then Wednesday, 18 bodies were left dismembered near Guadalajara.

The arrests started on Friday. A group of seven people were taken into custody.

Police said one of them, a woman known as "La Tosca," confessed to 20 killings and told authorities she was paid up to $50 a day to commit the murders.

Also taken into custody, Juan Mercado -- along with four of his alleged gang members. Police said Mercado was preparing to kill a group of victims. He later told reporters he had randomly chosen the people and was planning on torturing and killing them before dumping their bodies.

Later that same day, suspected Zetas hit man Jesus Hernandez Rodriguez was arrested for kidnapping and killing four U.S. Marines in April.

Then came Sunday and the 49 bodies left on the San Juan highway. It is a highway that leads to city of Monterrey, which is just over a 100 miles from McAllen and 75 miles from Roma, Texas.

Since the first of the year, authorities said there has been an escalation in the violence.

About 47,000 people have been killed in the drug related violence since 2006.