"We have received reliable information the guy is free," Sami Hassoun told The Associated Press from the northern Lebanese city of Tripoli, where the Marine has family.
Though he had not spoken with his brother, who was serving as a translator with the U.S. Marines in Iraq when he went missing June 20, Sami Hassoun said "we received a sign from my brother reassuring us."
He would not say what the sign was, but said the family received information deemed credible from a person he did not identify who came to their Tripoli home. That person, he said, did not disclose the whereabouts of the Marine to the family.
Lebanese Foreign Ministry officials said in Beirut that Lebanon's Embassy in Iraq had informed them Hassoun is still alive. They gave no further details.
Hassoun's family in Tripoli and in Utah have had their hopes dashed and raised with conflicting information about the Marine's fate coming from his purported captors and Lebanese officials.
On Saturday, a militant group calling itself the Ansar al-Sunna Army claimed on a Web site that it had beheaded the 24-year-old Marine, adding it would release video backing up that assertion. But the group said Sunday it did not issue the statement, leaving it unclear what had happened to Hassoun.
In a statement sent to Al-Jazeera television, a group calling itself "Islamic Response," said Monday that Hassoun was safe at an undisclosed location. The statement also claimed Hassoun had promised not to return to the American military.
"We pray that the news of his safe release is true," Tarek Nosseir, a family spokesman, said Monday. "If he is still in captivity, we remind the captors of the saying of our beloved prophet: Be merciful to those on earth, mercy will descend upon you from heaven."
Hassoun, educated at American schools in his native Lebanon before moving to the Salt Lake City area, was serving his second stint in Iraq.
His father, Ali Hassoun, who also lives in Tripoli, repeatedly has pleaded for his son's release. He and his other sons have contacted politicians and Muslim clerics in Lebanon and Islamist groups in Iraq in hopes of securing the Marine's release.
In West Jordan, Utah, Hassoun's family has stayed behind closed doors, reports CBS News Correspondent Lee Cowan, with only visits from the family imam and close friends. The community has responded, however, with tributes and a series of flags outside the modest home.