You can buy scores for choral pieces from GIA music, above.
This is a choral piece. Scores are available from Morning Star Music and JW Pepper.
A requiem in memory of the victims of the 1981 El Mozote Massacre, in which where a US-trained unit of the Salvadoran army killed 800 noncombatant peasants, was premiered at Baylor University’s Armstrong Browning Library in 2008. It has also been performed in Dallas by the Texas Voices, in El Salvador by the choir of the National Opera, and in Grand Rapids by the Choral Scholars.
For choir and orchestra. Pope Francis commissioned this piece for the 2018 canonization of San Oscar Romero de las Américas.