Now Playing: China threatens new tariff as trade war escalates

Now Playing: Dow tumbles more than 400 points amid Trump tariff crackdown

Now Playing: Maker of candy hearts and Necco Wafers sold

Now Playing: Usain Bolt stripped of his 9th Olympic gold medal

Now Playing: Van plunges from fourth floor of parking garage at Miami International Airport

Now Playing: Judge rejects 'stand your ground' claim in Corey Jones case

Now Playing: Newborn daughter of fallen hero does photo shoot with her father's fellow soldiers

Now Playing: Police: Uber driver said rider was shot during attack try

Now Playing: Hurricane season officially starts today

Now Playing: Lowest unemployment rate in 18 years

Now Playing: Alleged suspect captured in Tennessee deputy's killing

Now Playing: Police back at kidnapping suspect's home where bodies found

Now Playing: Police snatch woman from the edge of 180-foot Texas bridge known for suicides

Now Playing: 'GMA' Hot List: Serena Williams on her 'fourth trimester' struggle

Now Playing: Parents of teenage boy face prison, fines for treating his seizures with marijuana

Now Playing: Man in allegedly stolen vehicle leads police on slow-moving chase

Now Playing: Worker survives van plunge off parking lot's 4th floor

Now Playing: North Korean envoy hand-delivers letter to Trump

Now Playing: Uber driver allegedly fatally shot passenger on Colorado interstate

Now Playing: 12-year-old student works in college research lab