FIRST ON FOX: Sen. Josh Hawley, R-Mo., is raising the alarm about a massive number of "gotaways" at the southern border last year, after a new Congressional Budget Office report found that the number last fiscal year exceeded the population of Missouri's two largest cities combined. 

Hawley, in a letter to DHS Secretary Alejandro Mayorkas, cited the new CBO report which found that there were a record-setting 860,000 illegal immigrants who evaded Border Patrol agents in fiscal year 2023.

"These "gotaways" outnumber the combined populations of Kansas City and St. Louis, the two largest cities in Missouri," Hawley said. "At the very least, you owe the American people full transparency into what your Department knows about illegal immigrants who have entered our nation without being stopped or tracked."

BORDER PATROL OFFICIALS SAY THREAT POSED BY ‘GOTAWAYS’ AT SOUTHERN BORDER ‘KEEPS US UP AT NIGHT’ 

Senator Josh Hawley

 Sen. Josh Hawley, R-Mo., is seeking more information about getaways at the southern border. (Tom Williams/Getty Images)

The CBO report had found that DHS had not released official estimates for FY 23, but Mayorkas himself had testified that there had been over 600,000 gotaways. It then cited media reporting that the number was over 770,000.

"To account for the second group, people who crossed the border but were not observed or detected by CBP officials, CBO then adjusted the estimate of 750,000 people upward by 15 percent (or 110,000 people), to 860,000 people, following testimony by the Chief of the Border Patrol, who said that the estimated number probably undercounted those people by 10 percent to 20 percent," the report said.

The gotaways came amid a record fiscal year that saw over 2.4 million migrant encounters. Gotaways are particularly worrisome to officials as they are more likely to have something to hide, including criminal convictions, from officials. Jason Owens, now head of the Border Patrol, told lawmakers last year of his concerns over gotaways.

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"If a person is willing to put themselves into harm’s way crossing through very remote, very dangerous conditions to evade capture, you have to ask yourself why. What makes them willing to take that risk? That’s of concern to me," he said. "What’s also of concern to me is I don’t know who that individual is. I don’t know where they came from. I don’t know what their intention is. I don’t know what they brought with them. That unknown represents a risk, a threat. It’s of great concern to anybody that wears this uniform."

Hawley says the crisis has gotten worse under Mayorkas’ leadership.

"The yearly number of gotaways has increased dramatically under your watch, up from nearly 600,000 in fiscal year 2022 and more than double the 389,515 in fiscal year 2021," he says. "All told, nearly 2 million illegal immigrants have successfully evaded border officials during the Biden Administration."

He also cited reports that there were over 302,000 migrant encounters in December, itself a new record.

Dec. 18, 2023: Migrants flood into Eagle Pass, Texas, waiting to be processed. (Fox News)

"These unprecedented figures underscore the need for you to be fully transparent about your Department’s own accounting of the southern border crisis," he said.

He is asking for DHS to corroborate the CBO estimate, and to provide methodology of how gotaway estimates are calculated, and how many suspected terrorists, violent criminals and other felons are among them.

DHS has previously noted that gotaways have been an issue for multiple administrations, blaming it on a "broken" immigration system that is in need for reform and funding from Congress. The administration is seeking over $14 billion in border funding, which includes money for technology and staffing at the border. That funding is currently being held due to Republican demands for limits on asylum and the use of parole.

DHS has said that its investments in technology and personnel it has been able to make has led to high levels of apprehensions, including over 70% in 2021, and that the average rate has remained identical to the Trump administration, compared to around 35% between 2002-2004. 

The department says that there is also more awareness of who is getting in, even if they are not captured, due to those investments.

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"With the investments that this Congress has made in the Border Patrol, CBP as a whole, we have greater situational awareness now than I’ve ever had," then-Border Patrol Chief Raul Ortiz said in March last year.

Fox News reported on Tuesday that so far in FY 24 there have been over 96,000 known getaways, an average of 800 a day.

Fox News' Griff Jenkins contributed to this report.