The backstory to how Julian Assange overstayed his welcome in Ecuador's London embassy and was finally forced to leave included secret negotiations with the U.S. to wangle a pledge from Washington that we would not seek the death penalty for Assange's crimes.

It took nearly a year of back-channel talks, but the Justice Department finally relented and agreed not to subject Assange to the threat of capital punishment.

ABC News:

The process of moving Assange out of the Ecuadorian Embassy started a year ago, on March 7, 2018, when the Ecuadorians made their first request to the U.K.: a letter asking for written assurances that the U.K. would not extradite Assange to a country where he could face the death penalty, according to the Ecuadorian Interior Minister Maria Paula Romo.

Ecuador's direct outreach to the U.S. came six months later, through the country's ambassador to Germany, Manuel Mejia Dalmau, according to U.S. and Ecuadorian officials. Dalmau sought a private "emergency meeting" in Berlin with the U.S. Ambassador to Germany, Richard Grenell, viewed as one of President Donald Trump's closest envoys in Europe, the officials said.

Ecuador had become tired of paying for Assange's upkeep — $10 million in extra security and perks that Assange demanded.  The embassy's people were perfectly willing to throw him under the bus as long as the U.S. declined to seek the death penalty.

The challenge the Ecuadorans faced in turning him over to British officials, though, was the prospect of Assange facing the death penalty, which Ecuador strongly opposes.  Dalmau was blunt in his request, according to U.S. and Ecuadorian officials.

During one meeting, Dalmau asked whether the U.S. would commit to not putting Assange to death, according to a senior US. official.

Grenell then contacted the U.S Justice Department to see if he could provide assurances that the U.S. government would not seek the death penalty.  According to the senior U.S. official, Deputy Attorney General Rod Rosenstein consented.  That enabled Grenell to make the pledge.  The agreement between the U.S. and Ecuador was a verbal one, according to a source in the Ecuadoran government.

It's not unusual for a nation without the death penalty to demand that capital punishment be taken off the table before extradition is agreed to.  Great Britain has a law that prevents extradition to a country where the defendant could be executed.

The Extradition Act 2003 allows the UK to extradite individuals to certain countries, including the US, but removing someone to the authority of a foreign state is prohibited by statute if that person could face the death penalty — unless the home secretary gets adequate written assurance that it will not be imposed.

What's interesting about the Assange case is that the hacker has not been charged with a capital offense — yet.  The indictment alleges that Assange in 2010 "agreed to assist Manning in cracking a password stored on United States Department of Defense computers connected to the Secret Internet Protocol Network, a United States government network used for classified documents and communications."  Those crimes are punishable by up to five years in prison.

But the Justice Department has 60 days from the request for extradition to amend the charges.  It is widely expected that far more serious charges will be forthcoming against Assange because the hundreds of thousands of documents he is responsible for leaking contained sensitive and top-secret information.

Still, now that the U.S. has given verbal assurances that it will spare Assange's life, it's unlikely that any federal prosecutor will seek the death penalty.  This was not a difficult choice, as the federal death penalty is rare even in cases of treason and espionage.  So Assange will probably live out his life in a super-max prison.  His fears that the CIA will try to kill him while he's locked up will probably not be realized, given the intense security he will be under for the rest of his life.