With Gene Viernes, he was murdered in Seattle on June 1, 1981, while attempting to reform the Local 37 of the International Longshore and Warehouse Union (ILWU).

The union hall was only a block from a fire station; two firefighters arrived within minutes, and Domingo managed to tell them the names of the killers, "Guloy and Ramil".

[3] Pompeyo Benito Guloy and Jimmy Bulosan Ramil, both members of Local 37 and of the Tulisan gang, were found guilty of first degree murder and sentenced to life in prison.

[6][7][8] In 1991, former Local 37 president Constantine “Tony” Baruso (1928-2008) — a supporter of the Marcos regime — was also found guilty of aggravated first-degree murder in the death of Viernes but not Domingo.

[10][11] Silme Domingo and his fellow Local 37 labor activist Gene Viernes were among the 14 Marcos Martial Law era martyrs to be honored at the Bantayog ng mga Bayani memorial wall on November 30, 2011.