Jose Domingo Jasso-Topete is the second man to plead guilty in the March 24 incident, Immigration and Customs Enforcement said in a statement.
Jasso-Topete, 34, was among eight illegal aliens arrested after Border Patrol agents spotted five vehicles break through the border fence south of Animas, N.M.
All the vehicles were being driven without lights, and four of the vehicles collided with each other, ICE said.
Eight men in the four vehicles were arrested. Authorities said they found 6,953 pounds of marijuana in the vehicles.
The fifth vehicle escaped back into Mexico.
In a hearing Wednesday, Jasso-Topete pleaded guilty to conspiracy and possessing more than 1,000 kilograms of marijuana with intent to distribute.
He faces up to life in prison.
Another defendant, Francisco Flores-Enriquez, 26, pleaded guilty July 26 to conspiracy to possess marijuana with intent to distribute. He also faces a life sentence.
The other six defendants are awaiting trial after pleading not guilty.