The case of convicted terrorist-turned-US-citizen Vallmoe Shqaire raises questions not only about how Shqaire slipped past the enhanced vetting process implemented after 9/11, but also about why US law enforcement did not act more swiftly once his deception was discovered.

Federal authorities have been aware since at least 2010 that Shqaire was arrested on a bombing-related charge in Israel and served time in prison. They've had fingerprint evidence conclusively linking him to the terrorist act, committed under the name Mahmad hadr Mahmad Shakir, since early 2016, according to federal court records.

"Somebody dropped the ball," said Seamus Hughes, deputy director of the Program on Extremism at George Washington University.

Shqaire, 51, carried out the attack in Israel in 1988 "acting on the direction" of a cell of the Palestine Liberation Organization, at the time a terrorist group in the eyes of the US government, according to records filed in US District Court in Los Angeles.

Despite his conviction, which should have barred him from even entering the United States, much less becoming an American citizen, Shqaire's application was approved and he took the oath of allegiance on November 6, 2008, in the waning days of the second George W. Bush administration, the records state.

He was charged in September with illegally obtaining his American citizenship by intentionally withholding his criminal record and past associations.

"By concealing his violent, terrorist conduct, defendant circumvented the procedures our immigration system depends upon," prosecutors wrote in a sentencing memorandum.

Shqaire is currently free on bond and living in the Los Angeles area as he awaits his sentencing, scheduled for Friday.

Shqaire's case marks at least the second time a convicted terrorist has been made a US citizen after 9/11. Chicago-area resident Rasmieh Odeh pleaded guilty in 2017 to illegally obtaining her US citizenship by not disclosing her 1970 conviction in Israel for her role in a pair of bombings, one of which killed two people. Odeh, who became an American in 2004, has since been stripped of her citizenship and expelled from the country.

A spokesperson with US Citizenship and Immigration Services, an agency charged with combating immigration fraud and detecting national security threats, declined to answer detailed questions about the processing of Shqaire's application, citing a policy against commenting on matters involving pending litigation.

In a written statement, the spokeswoman said, in part, that the agency's current leadership "has enhanced the screening and vetting of those seeking immigration benefits to ensure they are eligible and do not pose a risk to national security."

A former US immigration official who was engaged in the vetting process in 2008 told CNN that a mandatory background check that was in place at the time should have detected something as egregious as a terrorism conviction, whether or not an applicant disclosed it.

The official, who spoke on the condition of anonymity due to the politically charged nature of immigration issues, added, however, that the system is only as good as the information it draws from -- some of it derived from foreign governments.

"Who knows whether this was in there," he said.

Shqaire declined to be interviewed for this article. His attorney, Mark Werksman, said in a recent interview his client has worked as a parking valet in Southern California for years and is not a threat to anyone.

His lies to US immigration officials, Werksman said in a sentencing memorandum, were a misguided attempt to escape the chaos of the Middle East for "the comparative peace and freedom of life in America."

"Mr. Shqaire wanted nothing more than to be an American and to contribute positively to American society," the lawyer wrote.

Despite his client's conviction, the case is an embarrassment for the government, said Werksman, a former federal prosecutor in Los Angeles.

"On paper, my client is a very bad guy," he told CNN. "So, the question is: How did this happen?"

The voluminous file on Shqaire in Los Angeles federal court spans decades and continents. There are references to the Six-Day War between Israel and its neighbors in 1967, the Palestinian uprising known as the first intifada that began two decades later, and claims of harsh interrogation techniques and coerced confessions.

Shqaire, a Palestinian-born Jordanian, says his family of 13 ended up in a refugee camp following the war among Israel, Egypt, Jordan and Syria. As a young man in the 1980s, he was recruited by the PLO and became a violent operative in its "Shabeba" cell, according to confessions obtained by Israeli military officials.

Shqaire underwent training with rifles and grenades and learned how to build bombs, the records state. He discussed the possible assassination of an Israeli intelligence officer and participated in the beatings of fellow Palestinians suspected of collaborating with the Israelis, including an incident in which a man was stabbed, according to the records.

In December of 1988, the records state, Shqaire and an accomplice built a pipe bomb. The accomplice placed it along the route of an Israeli bus. Shqaire served as a lookout and told the other man when the bus was in range. The bomb exploded, but no one was injured. The documents offer no explanation for the lack of injuries, despite the bomb detonating.

Shqaire would say decades later that his confessions were the result of coercive interrogations and threats by members of the Israel Defense Forces. He claimed he was beaten, subjected to showers that were either scalding or freezing and housed for "many weeks" in a dark cell that was so small, "I was unable to even stretch my legs or stand up."

He also accused Israeli authorities of repeatedly arresting his father as a means of intimidation, mistakenly shooting his brother in the belief that it was him, and of ousting his family from their home and sealing it shut with cement.

US prosecutors wrote in a court filing that "such allegations are not supported by the certified court records Israel provided." Nonetheless, prosecutors said they are not relying on Shqaire's purported confessions to the Israelis as part of their case against him.

Shqaire was sentenced to 10 years in prison in Israel in 1991 for, among other things, placing a bomb "with the intent to cause death or harm." A military appeals court later reduced the sentence to seven years. Shqaire was released after serving just four years following the 1993 Oslo peace accords and subsequent agreements.

He first came to the United States on a visitor's visa in 1999, records show.

That same year, he got married to a US citizen in a so-called green card marriage. He paid his bride, whom he first met on their wedding day, $500, the woman would later tell federal investigators. Read more at CNN