He found out that his brother-in-law (his first wife’s brother) had not died in the civil wars between Marius and Sulla as everyone had thought, but had, in fact, been taken into slavery. Oppianicus’ mother-in-law Dinea was overjoyed to hear her son was alive but Oppianicus was not. This interfered with his ability to inherit Dinea’s money. So he tracked down his poor brother-in-law, and killed him. And then poisoned Dinea.
