>>4639875 (Q lb)
Just a quick skim of wackipedia for assassinations in 1988. I couldn't find any mass shootings. If it was being trialed I think an overseas assassination would be the way to go to see if someone would overcome their base instincts…
March 29, 1988 Dulcie September, head of the African National Congress in Paris
April 16, 1988 Khalil al-Wazir, military leader of the PLO
1988 Chico Mendes, Brazilian environmental activist
KEK, probably the only year in the 80's in Columbia without an assassination…
India
March 8, 1988 Amar Singh Chamkila, controversial Punjabi singer/songwriter
Iraq
January 24, 1988 Mahdi al-Hakim, prominent figure in the Iraqi opposition
Pakistan
August 17, 1988 Muhammad Zia-ul-Haq, 10-year President of Pakistan and 12-year Chief of Army Staff
Philippines
January 17, 1988 Roy Padilla, Sr., Governor of Camarines Norte, and father of action star Robin Padilla.