Profile: Israeli spy Jonathan Pollard
Under pressure from prosecutors in 1985, Jonathan Pollard confessed to spying for Israel in exchange for them not seeking a life sentence.
But after a US judge reviewed a still-classified report from the US defence secretary about the damage Pollard had done to US intelligence, he gave him life in prison anyway.
Since then, numerous Israeli prime ministers and groups in both the US and Israel have called for clemency, a request rebuffed by a succession of US presidents, including Barack Obama.
In 2014, the fate of the former US navy intelligence analyst became the focus of last-ditch attempts to save faltering Israel-Palestinian peace talks.
The US reportedly considered freeing Pollard in exchange for concessions from Israel to the Palestinians - but the talks collapsed and prospects for Pollard's early release receded.
Wealth of information
Jonathan Pollard was born in 1954, and began serving as a civilian analyst in US navy intelligence near Washington DC in 1979.
Within several years, Pollard contacted Israeli intelligence and began offering classified materials. He soon came to be managed directly by an Israeli embassy official, passing reams of documents in return for regular payments and travel for him and his wife.
Pollard offered a wealth of intelligence information, including reconnaissance reports on the Palestine Liberation Organisation (PLO) offices in Tunisia, Iraqi and Syrian chemical-warfare production capabilities, and Soviet arms shipments to Syria and other Arab states, according to then-Jerusalem Post correspondent Wolf Blitzer.
Pollard had served on the American delegation of two intelligence exchanges to Israel and saw what was not being shared between the two close allies.
"I was very frustrated at the end of these two sessions. And the frustration builds," he told Wolf Blitzer, saying the information not being shared was "horrifying".
In 1985, just over a year after he began spying, Navy officials and the FBI interviewed him after hearing he had removed classified documents from his office.
Under the threat of an espionage prosecution, Jonathan and his wife, Anne, sought asylum at the Israeli embassy but were turned away. They were arrested soon after by the FBI.
Pollard admitted to spying for Israel in exchange for a promise from the justice department he would receive a "substantial" prison term, but not a life sentence.
He maintained he gave Israel classified documents because the US was not passing on important information. But some intelligence officials say he also offered information to other countries.
Israel initially denied Pollard had ever been a spy for the country, insisting he had worked with "rogue" officials. But in 1995, the Israelis made Pollard a citizen, and two years later, they admitted he was their agent.
Pollard spent nearly 30 years in prison, latterly at a medium-security facility in North Carolina. Anne Pollard was sentenced to five years and served two-and-a half. She moved to Israel after her release.
They divorced and Pollard remarried while in jail. His second wife, Esther, also moved to Israel, where she continued to campaign for his release.
In 1996 she went on hunger strike for 19 days to pressure the Israeli government to do more about her husband's plight.
Israel says Pollard's sentence was overly harsh, considering he was working as an agent for a staunch US ally.
US defence and intelligence officials strongly opposed his release for many years. In 1998 CIA director George Tenet threatened to resign if President Bill Clinton pardoned Pollard.
His eventual release removes a thorn from US-Israel relations, ending one of the longest-lasting sagas between them.