Department of Homeland Security Secretary Kirstjen Nielsen made her first appearance before the House Judiciary Committee on Thursday, and Democrats on the committee unleashed all their rage over her agency’s treatment of foreign-born minors and migrants in its custody.

Nielsen was bashed for the Trump administration's "zero-tolerance" policy that led to thousands of family separations over the summer, its handling of the migrant caravan, the death of a 7-year-old Guatemalan girl in Border Patrol custody, and a policy announced during the middle of Thursday’s hearing that bars asylum-seekers from entering the U.S.

Rep. Luis Gutierrez, D-Ill., said Nielsen held the "all-time record" for lying in an administration filled with liars when she tweeted this year that the administration did not have a family separation policy.

"There’s one thing this administration has done better than any other administration in American history, and that is lie," Gutierrez said. "But especially in the area of homeland security, lying has become elevated to an outstanding level of mendacity."

Nielsen responded: "Calling me a liar are fighting words. I'm not a liar. We've never had a policy for family separation."

Similar exchanges punctuated the heated hearing, where Democrats repeatedly questioned her agency's actions along the southern border and Republicans repeatedly praised Nielsen for carrying out President Donald Trump's policies to cut illegal immigration and reduce legal immigration.

At one point, as Rep. David Cicilline, D-Rhode Island, questioned her about policies that deal with the detention of minors in Homeland Security custody, Nielsen responded angrily.

“Would you like me to answer the question or do you want to just yell at me?” she shot back.

Nielsen has headed Homeland Security for 14 months, and her job security has been in question in recent months as rumors have swirled over her standing with Trump. She has implemented some of his most controversial policies, including multiple attempts to limit asylum along the southern border and the deployment of nearly 6,000 active-duty military troops there — it was a Homeland Security request that prompted the Department of Defense to mobilize those troops.

Nielsen repeatedly defended her department's actions, saying her agents are dealing with an unprecedented wave of asylum-seekers that has overwhelmed the U.S. immigration system and requires massive changes in U.S. immigration law.

She told the committee that Customs and Border Protection needs more officers to man the nation's ports of entry, that Border Patrol needs more agents to patrol regions in between, and that the southern border will never be completely secure until the U.S. completes a "wall system" including a combination of walls, fencing, and technology.

And she repeatedly asked the members to update U.S. laws that allow unaccompanied minors and family units to apply for asylum and remain free in the country.

"This crisis is the direct result of loopholes created by federal law and adverse federal court rulings that prevent the detention and repatriation of illegal unaccompanied alien children and family units," she said.

Several Republicans defended Nielsen during the hearing, including Rep. Tom Marino, R-Penn., who apologized to Nielsen for the way she was treated by Democrats on the committee.

"I'm embarrassed by the performance that was done here," Marino said. "It's uncalled for, it's ungentlemanly, and it's nothing more than grandstanding."

But Democrats made clear that they are far from finished with Nielsen. Rep. Jerry Nadler, D-N.Y., who will become committee chairman in January when Democrats retake control of the House.

"I want to put you and the department on notice: the time for accountability has arrived," Nadler said.