WASHINGTON (AP) — An American man who is marking four years in prison in Cuba has written a letter to President Barack Obama asking the president to get personally involved in securing his release.

Alan Gross was arrested four years ago Tuesday while working covertly in the Communist-run country to set up Internet access for the island’s small Jewish community, access that bypassed local restrictions. At the time, he was working as a subcontractor for the U.S. government’s U.S. Agency for International Development, which works to promote democracy on the island.