The heads of more than 40 American Jewish organizations have sent a letter to Cuban President Raul Castro asking for the release of Alan Gross, a Jewish American social worker who has been imprisoned in Cuba since 2009 on charges of spying.

“As the Jewish holiday of Passover, which celebrates freedom, approaches, we respectfully appeal to you to release Mr. Gross on humanitarian grounds and allow him to reunite with his family,” reads the letter from the Conference of Presidents of Major Organizations. “Passover is a particularly symbolic time since it recounts the Jewish people’s release from bondage in ancient times, and your gesture would be especially appreciated.”

Gross, 62, of Maryland, was in Cuba on a mission for the United States Agency for International Development, bringing Internet access to the country’s Jewish community, when authorities arrested him for “crimes against the state.”
In a meeting with US Senators in February, Castro reportedly acknowledged that Gross “was no spy,” but refused to release him.

American Jewish organizations have since stepped up efforts to attain freedom for Gross, with the Jewish Federations of North America even appealing to Pope Benedict XVI to seek his release. A prominent New York rabbi met with Gross before Purim, describing him as hopeful and upbeat.

But Gross has reportedly lost a significant amount weight during his imprisonment, and he is concerned for his family, as both his daughter and his mother have been treated for cancer since his incarceration.