Now Playing: In Memoriam for February 2018

Now Playing: High school valedictorian addresses grads through bullhorn following speech ban

Now Playing: This Memorial Day weekend, honoring those who lost their lives in non-combat accidents

Now Playing: New details about North Korea meeting with South Korea

Now Playing: Hero saves highway driver from car on fire

Now Playing: Border Patrol agent accused of shooting and killing woman in Texas

Now Playing: American held in Venezuelan prison returns to US

Now Playing: Changing wind pattern raise fears of dangerous toxic gases in Hawaii

Now Playing: Gulf Coast braces for Alberto as storm threatens to ruin holiday weekend

Now Playing: Subtropical Storm Alberto is picking up speed and getting stronger

Now Playing: 20-year-old woman shot and killed by border patrol agent in Texas

Now Playing: American citizen and his wife freed from captivity in Venezuela

Now Playing: USC's president steps down after sexual assault allegations against campus doctor

Now Playing: Hero science teacher takes bullet for his students

Now Playing: Property taxes spike, shocking homeowners nationwide

Now Playing: Raging fire at landfill outside Portland

Now Playing: Donor recipient receives new heart after six-year wait

Now Playing: Heroic teacher tackled middle-school shooter after running toward bullets

Now Playing: Airline passenger arrested after alleged midair tirade over alcohol

Now Playing: Grandparents convicted of kidnapping in international custody case