Hersh Goldberg-Polin was one of the hundreds of hostages taken by Hamas during its attack on Israel on Oct. 7, 2023. The 23-year-old Israeli-American was held for more than 300 days before being killed in late August by his captors as Israeli troops were moving in.

His parents, Jon Polin and Rachel Goldberg-Polin, have been leading voices in the effort to bring their son and the other hostages home, and they told CBS News they'll continue to advocate for the roughly 100 still being held captive in the Gaza Strip.

Hersh was kidnapped by Hamas terrorists from the Nova music festival on Oct. 7, and about six months later, Hamas released a video of him alive. But in August, Israeli soldiers found his body, along with those of five other hostages, in a tunnel in Gaza.

His parents' dignity and courage has never wavered, not even when they learned how Hamas had executed their son.

"He had a bullet that went through his hand. ...The gun was so close that the bullet was able to go through his hand, through his neck and come out the side of his head," Rachel Goldberg-Polin said. "He then, we think, collapsed, and they put the gun on the back of his head. And the exit wound for that gunshot was the top of his head."

She said her son, despite being nearly six feet tall, weighed just 115 pounds when he was buried last month. She said that she didn't necessarily want to know the more horrific details of her son's death at first, but then she saw how small his body looked at the funeral.

"I just think that that's really important, first of all, for people to understand how these hostages are being kept and treated, because we do have these 101 that are still there," she said.

The Goldberg-Polins both place the blame for their son's death foremost on Hamas, but both also say they feel Israeli, American and even global leadership has let them down.

"There is a role the world's leaders can play and we feel like we were failed," Jon Polin said "We were failed by Israel's leaders. We were failed by all of the world leaders. And we hope that we can now turn this into action while it's still possible to save the 101 [hostages]. ... We sat and we waited for the presidents and prime ministers and foreign ministers of those countries to get up on a stage, arm in arm, and demand our people be let go. And that didn't happen. It still hasn't happened. Maybe now it can. Maybe they'll use this as a corrective."

He also stressed the need for a diplomatic solution to return those still being held.

"In 369 days, seven hostages have come out through military operation. Over 100 have come out through a negotiated settlement. It's pretty clear that what we need to do. Some people have this vision that, the idea of soldiers are going to come out carrying 101 hostages. Most people understand that to get these people out is going to require a negotiated agreement of some sort," he said.

In their personal lives, the Goldberg-Polins now face the heartbreak of adjusting to life without their son.

"I'm trapped right now in this place psychologically, where I'm scared to turn around and look back," Rachel Goldberg-Polin told CBS News. "And I'm scared to try to proceed forward in life without Hersh.

"I moved my seat at our breakfast table," she added. "So I sit where Hersh normally sat because I didn't want to see him not in his seat." 

"It's very confusing now because we had his absence for a very long time before he was killed," she said. "But there was always this feeling, there's hope and this optimism that we'll get him. We will get him home."

The couple remains focused on helping bring the remaining hostages home safely. But as the war widens, there appears little political will for negotiation right now on either side. They are hoping that changes. 

"I'm very hopeful that within that widening, that there's opportunity — meaning whatever's happening in Lebanon, it's horrible for everybody. The whole region is on fire. Whatever's happening with Iran last week firing 180 ballistic missiles at Israel; will Israel retaliate? ... Maybe there's room somewhere to say everybody, nobody is doing well right now. We're going to stop this," Rachel Goldberg-Polin said.

The couple, both Orthodox Jews, say they have seen tremendous support from both the Jewish community and also many Christians around the world. Despite the tragedy, both still find comfort in their faith.

"My faith in god has not diminished," Rachel Goldberg-Palin said. "My faith in people has, because I felt, I just felt that people could have done more."