Now Playing: Severe storms, threat of twisters after flash flood emergency in Okla.

Now Playing: Famed designer Kate Spade committed suicide by hanging: Medical examiner

Now Playing: Calls for police department probe after video shows violent arrest

Now Playing: ATF says agents 'ambushed' during undercover operation

Now Playing: Pet monkey gets loose, attacks Home Depot worker

Now Playing: Teen who captured hearts when he asked for a family graduates

Now Playing: Melania Trump's office responds to Giuliani's comments on adult actress

Now Playing: 15 years later teen girl reunites with EMT who treated her

Now Playing: Video captures emergency landing on busy interstate

Now Playing: 2 tourists stabbed to death at Circus Circus hotel in Las Vegas

Now Playing: Elite NYC private school faces sexual abuse allegation by former student

Now Playing: Trump says he would invite Kim Jong Un to the US if summit goes well

Now Playing: 'GMA' Hot List: Grandmother freed from jail is grateful 'Trump had mercy on me'

Now Playing: Chicago man killed by police is 'going to get justice,' family says

Now Playing: Trooper pulls over cop who delivered him in 1991: 'His mouth dropped -- so did mine'

Now Playing: How parents can prevent hot car fatalities

Now Playing: ATF agent shot in line of duty in Indiana

Now Playing: Aerial view of Kilauea Volcano's lava flowing, pouring into the ocean

Now Playing: Nancy Grace and Dan Abrams on Alice Johnson's commutation & more

Now Playing: Trump commutes sentence of Alice Marie Johnson