The body count is already at 20 and investigators in the Juarez valley are still looking for more.
The tip on that mass grave found just across the border from El Paso's Lower Valley came from U.S. Homeland Security investigators.
"U.S. Immigration and Customs Enforcement's Homeland Security Investigations routinely collaborates and works closely with its Mexican law enforcement partners," HSI officials said in a statement to ABC-7. "In this case HSI shared intelligence it received from various independent sources regarding the possible existence of mass graves in the outskirts of Ciudad Juarez, Mexico."
On Monday, Nov. 26, investigators found nine more skeletons in the Juarez valley, increasing the total to 20.
They said that they are still digging.
The Mexican attorney general's office says the victims were buried about two years ago when violence peaked in Ciudad Juarez as drug cartels fought bloody battles leading to multiple killings each day.
More than 3,000 people were killed in 2010 in Ciudad Juarez.