Scores of foreign nationals, recruited by the FBI as witnesses and informants, disappeared between 2015 and 2017 in the United States, according to a new audit.

The Justice Department's inspector general said in an audit released Wednesday that in many cases, the Federal Bureau of Investigation failed to report the missing foreigners to immigration authorities.

The audit looked at the Justice Department's use of immigration programs that allow law enforcement agencies such as the FBI and the Drug Enforcement Agency (DEA) to sponsor foreign nationals for temporary stay in the United States.

David Gomez, a retired FBI special agent, said foreign individuals sponsored by the FBI are primarily criminal informants or national security assets.

"Most are probably undocumented aliens of some sort, or people brought in from overseas to perform some special criminal, counterterrorism, or counterintelligence mission," Gomez said.

Missing not reported

The audit found that the FBI and DEA did not always keep close tabs on their foreign recruits and, in some instances, failed to alert the Department of Homeland Security when they went missing.

"We are concerned that the monitoring policies and practices currently executed by the DOJ components that sponsor foreign nationals do not adequately mitigate the risks associated with bringing individuals into the United States who may have criminal backgrounds or involvement in disreputable activities, or who may be associated with such individuals," the report said.

A total of 61 FBI-sponsored foreign nationals "absconded" from the bureau's control, the audit found. While the bureau reported 39 missing individuals to the Department of Homeland Security, it failed to do so in 22 other cases until after the department had begun inquiring. One DEA-sponsored individual was also found to have absconded.

The total number included "deliberate" absconsions by individuals who purposely evade law enforcement, as well as "benign" cases where people change their places of residence without informing their sponsoring agency. The report did not provide a breakdown of the two categories, nor did it reveal the nationalities or whereabouts of the absconding individuals.

Legal limbo

Records show nearly 5,500 foreign nationals were sponsored by law enforcement agencies between 2015 and 2017. In about one-fifth of the cases, the audit found that immigration sponsorships and visas had expired, leaving them in legal limbo.

The inspector general said both the FBI and DEA have accepted its recommendations, including taking actions to help the Department of Homeland Security in locating absconding individuals.

Absconding is not limited to law enforcement. In recent years, hundreds of foreign military trainees visiting the United States have gone missing. In 2017, the inspector general for Afghanistan reconstruction reported that between 2005 and 2017, 320 foreign trainees, nearly half of them from Afghanistan, went missing in the United States.