Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

WASHINGTON — For months, Egypt ignored paperwork that could have allowed an American to be released from prison outside Cairo and instead the 54-year-old man from New York died behind bars earlier this month, according to his lawyer and a Democratic senator.

Moustafa Kassem, 54, who was arrested in 2013 and charged with terrorism-related offenses that both the U.S. government and human rights groups said were baseless, died on Jan. 13. He was a diabetic who had been on a liquids-only hunger strike since his conviction in an Egyptian court in September 2018.

Egypt had told U.S. officials that Kassem would be eligible for release and deportation to the United States if he renounced his Egyptian citizenship. Kasseem dropped his appeal of his conviction and submitted papers to relinquish his Egyptian citizenship more than six months ago, his lawyer, Praveen Madhiraju, told NBC News.

But Egypt took no action, despite appeals from Vice President Mike Pence, who had urged Kassem's release with Egyptian President Abdel Fatah al-Sisi two years ago and with the country's foreign minister as recently as December.

Although Pence took a personal interest in Kassem's case, the Trump administration generally has failed to place sufficient pressure on Sisi's regime and has allowed about $1.2 billion in annual U.S. military assistance to keep flowing to Cairo, Madhiraju said.

The administration raised the issue "but they didn't do everything they could have," the lawyer said.

Trump has avoided public criticism of Sisi and called him his "favorite dictator."

Asked if the Trump administration would impose penalties on Egypt over the death of Kassem, a State Department spokesperson said, "We are reviewing our options and consulting with Congress."

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

As for accusations the administration has failed to press Cairo over human rights, the State Department spokesperson said, "We raised our concerns about Mr. Kassem’s health and the need for his immediate release with the Egyptian government at the highest levels; and will continue to raise our serious concerns over human rights and Americans detained in Egypt at every opportunity, as will the entire team at the State Department."

The White House declined to comment.

"I'm extremely troubled that the Egyptian government chose to sit on the paperwork to release Mustafa Kassem for months, essentially sealing his fate to die in their prisons," Democratic Sen. Chris Murphy of Connecticut said in a statement.

Sisi has overseen "a brutal crackdown on political dissent," Murphy said. "But President Trump's complete disregard for human rights abroad clearly sent a signal to Sisi and others that they don't have to take American requests on these issues seriously."

Murphy cited legislation that imposes conditions on $300 million in military aid to Egypt, and urged the administration to hold up the assistance to Egypt over its human rights record.

"The fact that Egypt continued to detain Kaseem, despite numerous high-level requests from the U.S. for his release, is an indication of how weak US diplomacy has become," said Andrea Prasow, of Human Rights Watch.

"I'm sure the Egyptians found the US demands somewhat empty in the face of the billions of dollars in U.S. military aid that continued to flow their way regardless of their rampant human rights abuses, including of U.S. citizens."

The State Department informed the Senate Foreign Relations Committee about Egypt's inaction in the case on Tuesday, according to a letter obtained by NBC News. Congress recently adopted legislation requiring the Trump administration to keep lawmakers regularly informed about the status of Americans detained by the Egyptian regime.

"At the time of his death on January 13, 2020, all legislative processes regarding his renunciation of his Egyptian citizenship had been completed, and we were waiting for the Ministry of Interior to rule on his citizenship renunciation request," the State Department's Bureau of Legislative Affairs wrote. "According to the Egyptian government, he would have been eligible for deportation upon final revocation of his citizenship."

Mohammed Soltan, another American who was imprisoned with Kassem, was released about two weeks after he signed papers renouncing his citizenship, he said. Soltan was freed in 2015 after nearly two years in prison and following a hunger strike that gained international attention.

In this March 9, 2015 photo, Mohammed Soltan is pushed by his father Salah during a court appearance in Cairo, Egypt. Heba Elkholy / AP

Soltan, who grew up in the United States, had initially refused to give up his Egyptian citizenship. But his sister explained that was the only way he would be able to win his release, Soltan said.

"It was a choice between my freedom and my citizenship, and I chose freedom," Soltan said.

He said Egypt had other ways of releasing imprisoned Americans or other foreigners apart from requiring them to give up their Egyptian citizenship, and it was merely a question of the regime's political will.

There are several other Americans currently imprisoned in Egypt, according to human rights advocates, including Reem Mohamed Desouky, a schoolteacher from Pennsylvania who was arrested at Cairo's airport and accused of criticizing the regime on Facebook.

Before his death, Kassem, who was married with two small children, had made a desperate appeal to President Trump. In a letter smuggled out of Tora prison, he wrote: "I am putting my life in your hands."