The failure occurred, in part, because older fingerprint records were not digitized as part of DHS or the FBI fingerprint databases and therefore could not be readily searched thereby preventing those who had been ordered deported or removed from being identified.
The Department of Homeland Security Inspector General report
said there are still "about 148,000 older fingerprint records that have not been digitized of aliens with final deportation orders or who are criminals or fugitives."
Failure to digitize these records risks "making naturalization decisions without complete information and, as a result, naturalizing additional individuals who may be ineligible for citizenship or who may be trying to obtain US citizenship fraudulently," the report added.
"US Citizenship and Immigration Services granted US citizenship to at least 858 individuals from special interest countries who had been ordered deported or removed under another name," according to the Department of Homeland Security Inspector General report
The report describes special interest countries as "generally defined as countries that are of concern to the national security of the United States."
At least one of the people identified as having improperly been granted citizenship is now working in law enforcement, the report said.
It recommends the remaining older fingerprint records be digitized and that DHS review "the eligibility of each naturalized citizen whose fingerprint records reveal deportation orders under a different identity" and decide whether to seek denaturalization.
The report noted that the department has concurred with its recommendations and has begun implementing corrective actions.
Department of Homeland Security spokesperson Neema Hakim told CNN that "DHS is and has been taking steps to address this issue" including working to digitize the 1990s-era fingerprint records.
But Hakim added, "The fact that fingerprint records in these cases may have been incomplete at the time of the naturalization interview does not necessarily mean that the applicant was in fact granted naturalization, or that the applicant obtained naturalization fraudulently."
"Where the DHS review process finds that naturalization was obtained fraudulently, DHS will appropriately refer the case to the Department of Justice for civil or criminal proceedings, including for denaturalization," Hakim said.
"This failure represents a significant risk to America's national security as these naturalized individuals have access to serve in positions of public trust and the ability to obtain security clearances," Republican Sen. Ron Johnson of Wisconsin, the chairman of the Senate Homeland Security and Governmental Affairs Committee, wrote in an open letter to Secretary of Homeland Security Jeh Johnson.
Failure to properly screen applicants for US citizenship, particularly from "special interest countries," is likely to further fuel controversy over the screening of immigrants, a contentious topic during the 2016 election cycle.
Republican presidential nominee Donald Trump has called for immigration bans targeted at countries with connections to terrorism. He had previously called for a temporary prohibition of Muslim immigrants.
The apprehension of Ahmad Khan Rahami, the suspected perpetrator of the recent bombings in New York and New Jersey, is similarly likely to draw attention to the screening process as Rahami immigrated to the US from Afghanistan and subsequently was granted US citizenship.