The acting director of U.S. Immigration and Customs Enforcement says DNA testing this year helped detect more than 1,000 fake families crossing the southern border.

"We are utilizing DNA sampling right now in the border environment trying to ferret out the false families," Matthew Albence said Thursday in the White House press briefing room.

DNA testing began in May as a pilot program amid a surge in Central Americans seeking asylum. Due to a 1997 legal settlement, children must be released after 20 days of detention, which resulted in the release of many family units.

Albence said that "we are hitting about a 15% rate of individuals or families presenting as families that really aren't families, and we are prosecuting those cases."

Initially, a pilot program had revealed an approximate 30% rate of false families, the Washington Examiner first reported. Before the May introduction of DNA testing, authorities relied on document analysis and other methods of investigation.

In a phone call following the briefing, an ICE spokeswoman clarified that only 1,020 family units had been subjected to DNA testing, of which 155 were determined to be fake. More than 800 additional prosecutions of phony parents resulted from non-DNA evidence.

Albence did not tell journalists the reason for his visit to the White House or say if he met with President Trump. Albence previously took the briefing room podium two weeks ago to blast "sanctuary" city laws. He began his Thursday address rebuking a court ruling last month that limited ICE reliance on electronic databases to establish probable cause to detain people suspected of being in the United States illegally.

White House briefings have not been given by one of Trump's representatives since March, but agency leaders have given many briefings. On Tuesday, acting Director of U.S. Customs and Border Protection Mark Morgan touted a decline in border apprehensions after he also appeared last month.