The 64-year-old man made aliyah to Israel 20 years ago, and received the status of a prisoner of Zion after he was imprisoned by Yemini authorities for hanging an Israeli flag outside his home.
"I'm very concerned about him," his daughter said. "If he had arrived there, I believe he would've contacted us. I'm very much afraid he was captured by ISIS. Unfortunately, no one is helping us."
The man has four daughters - two who live in Israel and two others who live in London. Since he made aliyah in 1995, he has returned to his birth country four times using his foreign passport.
During his last visit in 2013, he was detained for three months on suspicion of spying for Israel, and was only released when rebels tried to take over the city, leading authorities to free all detainees.
The man went back to the war-torn country to bring his brother, who was left behind in Yemen, to Israel. "We tried to convince him not to go but it didn't help," his daughter said. "He told me not to worry because he would only be there for a few days."
The man left Israel for Jordan on June 1, but could not find a connecting flight to his destination. He spoke to his family the next day, telling them he had met three Saudis who were heading to Yemen and have agreed to take him.
"I asked him how much money will it cost, and he said they were taking him for free," his daughter said. "That's when I started suspecting. Why are strangers not taking money? He didn't listen to me, and I don't know what has happened to him since. After a few weeks, we made inquiries and we were told he didn't make it there. I contacted someone in Jordan and I was told he left Jordan, but they didn't know where he went."
The family contacted the Foreign Ministry in Jerusalem, but was told they could not help because Israel has no diplomatic relations with Yemen. In addition, the family learned that after his last visit to Yemen, the man was summoned for questioning by security officials, who warned him he must not go to Yemen again.
"No one is helping us and I'm depressed," the daughter said. "My father knows that country like the palm of his hand, and that's why he wasn't afraid to go. I think he left Jordan but I don't think he made it (to Yemen). We were offered to pay money to a third party who would try to search for my father, but we have no money to pay."
The Foreign Ministry declined to comment on the story.