Federal immigration officials assigned to the U.S.-Mexico border are seeing an uptick in the number of instances in which investigators have been able to identify unrelated migrants posing as families in an effort to evade immediate deportation after they have illegally crossed into the country.

From mid-April through May 31, Immigration and Customs Enforcement interviewed 1,126 people who claimed to be traveling with a family member when they were taken into custody. Of that group, 206 "fraudulent families" were found to have fabricated familial relations either by verbal statements or with bogus legal documents. A family consists of two or more people, according to ICE.

The agency uncovered 422 fraudulent paper documents or verbal claims in that six-week portion of its continuing investigation.

ICE presented 399 cases for prosecution to the Justice Department and has had 315 accepted.

The new figures indicate an uptick in the rate at which ICE is identifying unrelated migrant families. On May 1, ICE said it had seen 29 such cases since April 18. Forty-five cases were referred for prosecution for fraud and the U.S. attorney’s offices accepted 33 of those referrals.

A total of 58,000 people claiming to be part of a family crossed the border in April alone. Despite the small rate of unrelated families, ICE's new acting Director Mark Morgan, said the trend must be addressed.

Morgan, who took over the agency earlier this month, said he is pushing the Justice Department to take up as many of these cases as it can.

"I know you hear from all agencies about consequences — that’s the hallmark of the rule of law. It’s not enough to do great investigative work to uncover this. We have to work with DOJ to make sure we’re prosecuting these individuals who exploit kids — should be prosecuted to the full extent of the law," Morgan told reporters earlier this week.

ICE has tasked 400 Homeland Security Investigations personnel with looking into incidents where a family is not believed to be related, an adult is posing as a minor, or a child is being "recycled" by human smugglers and inserted with random adults. Unlike adults, families must be released from ICE after 20 days in custody.

The Department of Homeland Security began sharing in March concerns about unrelated Central American families at the southern border.

“One of the things that we've seen a huge increase in and our partners in CBP [Customs and Border Protection] have seen, too, is the use of fraudulent documents,” Derek Benner, ICE Homeland Security Investigations deputy director, said during a speech at the Border Security Expo in San Antonio, Texas.

ICE commenced a days-long pilot in May with ANDE, a DNA testing company that can be completed in 90 minutes and in remote locations, including on the border.

Approximately 30% of rapid DNA tests of migrants who were suspected of arriving at the southern border with children who weren't theirs revealed the adults were not related to the children, the Washington Examiner reported last month.

The pilot was stood up for a few days in May and carried out in McAllen, Texas, and El Paso, Texas. The debut marked the first time DNA testing of any sort has been used at the border. Currently, ICE and U.S. Customs and Border Protection must use verbal statements and written documents to verify family connections.

Sixty percent of people apprehended at the southern border in April were Central American families, not single adults from Mexico, which historically made up the majority of illegal crossers.

Roughly 249,000 migrants of the total 460,000 people who were arrested for illegally crossing the southern border this fiscal year have claimed to be traveling with a family member were taken into custody between October and April.