The victim, 18-year-old Stephanie Benton, was placed in a 55-gallon drum and left in a Lake Elsinore field.
Jeffree Jay Buettner, 34, and Glen Joseph Jones, 26, were convicted by two separate Riverside County juries of first-degree murder.
Both juries also found special circumstances.
The two panels will begin hearing testimony next week in the penalty phase of the trial.
Benton's badly decomposed body was found in a 55-gallon drum in an open field near Nichols Road and Collier Avenue in Lake Elsinore.
Prosecutors say Benton was beaten and strangled by her killers.
There was a leather belt around her neck and her head was completely wrapped in duct tape.
Prosecutors say Buettner and Jones murdered Benton because she had been talking to law enforcement officers about crimes the two men had been committing.
Both men now face the death penalty.