The family of freed American hostage Keith Siegel said he was deprived of both food and sunlight during his 15-months hell. Now, the 65-year-old North Carolina native is eager to help the hostages still under Hamas captivity in any way he can.

It is believed that at least two of the six American hostages still held in Gaza are alive — Sagui Dekel-Chen, 35, who grew up in Bloomfield, Connecticut, and Edan Alexander, 19, from Tenafly, New Jersey. Four other Americans are believed to have been killed in captivity.

“Father is on the list!” Siegel’s wife, Aviva Siegel, exclaimed in a video as she hugged her daughter. The video, posted by the Israeli-language newspaper Israel Hayom, was taken by Siegel’s daughter Shir Siegel on the streets of Israel.

NBC News' Yasmin Vossoughian speaks with Lee Siegel, brother of released Israeli-American hostage Keith Siegel, about their long-awaited reunification.

American-Israeli Keith Siegel was released by Hamas Saturday morning in the latest hostage-for-prisoner swaps — making him the first US citizen freed by the terror group under the ongoing cease-fire deal.

Hamas on Sunday published a letter purportedly written by former Israeli hostage Keith Siegel before his release, in which he thanked his captors and criticized the Israeli government His family says

The current ceasefire started Jan. 19 with Hamas agreeing to return 33 hostages and Israel to release over 1,800 Palestinian prisoners. Hamas has released over a dozen hostages so far, and on Monday, Israeli officials said eight of the remaining hostages were killed.