>> Deep in remote mountains.

Overseas teams of researchers, archaeologist and military personnel are searching for fallen American soldiers and a team at the University of Illinois.

Chicago is part of that effort.

Join Hernandez tells us more about their mission to bring the missing home and the families still fighting for closure.

That's where I want to go.

>> Inside the Department of Behavioral Sciences is a team of researchers working to find missing American soldiers.

>> We were looking for an aircraft crash That's Rick Elliott and Jessica Bishop.

>> The Boe for Ku AC Center for the Recovery and identification of the missing known scram.

>> We get to participate in this mission to bring service members home and help families.

>> They work in partnership with the federal agency known Defense P O W M I a accounting agency or DPA 8.

>> Its mission is to bring families the long-awaited answers.

The agency brings together teams to locate, recover and identify U.S.

service members who were killed in past conflicts and never brought home.

This team searches for World War.

2 soldiers in the Philippines supports missions in countries like Vietnam and Italy.

>> First, we'll do this historical research too.

Figure out what happened in each case to see if we can find the location.

You know, where the aircraft might have crashed.

>> So far, Elliott has been on 6 trips and he's preparing for his 7th to the Philippines.

>> This is a metal detector more advanced one.

So it's able to give you a more accurate reading of what you are detecting.

Not just that it's metal.

I've gone on investigations and work in places where there's no cell signal.

You're strictly on the SAT phones and that's the only way that you can get word out.

>> Last year, Crim and the dpa made a major breakthrough locating 5 American soldiers alongside a mountainside in Laos.

>> Bordering Vietnam.

One of them was U.S.

Air Force Tech.

Sergeant Willis are hall.

His son tells us he was just 18 when his father deployed.

>> When they told me that they had found my father's remains.

It was like to hit in the chest.

Took my breath away.

You know, I completely broke down.

And that because it was something that I thought I would never see.

>> Steve Coll says his father along with 18 other men were part of a secret operation run by the United States.

What a tactical air navigation radar site and a remote mountain in Laos.

Recall INS father was among them.

He was 8 years old when his father left when the site was overrun.

In 1968, 11 men were killed and among them were Rick in Steve's fathers, their families waited for answers for years.

Rick's mother sued the U.S.

government to release information and the mission was finally declassified in the early 1980's.

Last year, Rick stood on the very mountain where his father likely took his last breath.

>> If it hadn't been for the if it hadn't been for their health.

>> I probably never would have made it a point out and I definitely would never got the helicopter right around which the most powerful when you can take out the full spot on the side of the mountain, realize that that's the.

>> The PA guys.

>> For cram every excavation site tells the story.

Jessica Bishop says it represents a name, a family and a commitment to bring soldiers home.

>> You're dealing with weather and logistics and we don't stop taking until we know that.

Okay, we've done all we can.

>> such a rewarding being able to.

Help to provide answers to these families that have been waiting decades for them.

>> That was just overwhelming for Steve Hall, the discovery of his father's remains is news.

He's waited nearly 60 years to hear.

>> We did so many things together.

So not only did I lose, probably my best friend, but I lost my father.

>> These kids.

That don't even know.

And they're literally risking their lives.

>> For Chicago tonight, join Hernandez.

>> 4 soldiers remain unaccounted for among the 11 men killed during the Lima site mission.

Recalling says he's staying hopeful in his search for his father.

He