Law & Order (1990) : 17x13

The shooting of university student Jason Miles at a political rally hosted by controversial speaker Judith Barlow leaves any number of suspects, but after Green and Cassady prove that two of the people they've questioned are lying about their alibis, they turn their attention to Malcom Yates, a grad student who claimed to be with Jason's girlfriend at the time of his death. McCoy and Rubirosa realise that Yates went after Barlow because of her open criticism of stem-cell research, something that Yates had high hopes could help find a cure for his own Parkinsons.