The Unforgotten

In 1993, fishermen discovered the body of Shelley Watkins floating in the Trinity River in Texas. The young, wealthy mom had been wrapped in black plastic and weighed down by concrete blocks. Investigators say they know exactly who killed Shelley and threw her in the river. They say they have strong evidence to back up their claims. If so, why has no one ever been held accountable for Shelley's murder?