(NewsNation) — House Republicans launched an investigation into what they’re calling Department of Homeland Security Secretary Alejandro Mayorkas’ “dereliction of duty” at the southern border.

On Wednesday, the House Committee on Homeland Security held a hearing, called “Open Borders, Closed Case: Secretary Mayorkas’ Dereliction of Duty on the Border Crisis,” a little more than a month after the expiration of Title 42, a policy that allowed the United States to expel migrants at the border.

Data shows that, despite officials and lawmakers warning of a “surge” of migrants coming to the United States after Title 42 ended, border crossings went down dramatically.

Still, cities are grappling with the number of migrants who have already entered the country as U.S. Customs and Border Protection saw record numbers of crossings in the last year.

Big groups of migrants continue to be bused to cities such as New York, Chicago and Washington. In New York, city officials have opened a number of emergency shelters.

Rep. Mark Green, R-Tenn., the Homeland Security Committee’s chairman, has accused Mayorkas of making reckless policy decisions.

Since Mayorkas’ first day in office, Green said Wednesday, the American people “have suffered from a national security, humanitarian and public safety disaster” at the southern border — a disaster the lawmaker said has turned “every city into a border city and every state into a border state.”

Green claimed a “mountain of evidence” gathered by the Homeland Security Committee shows Mayorkas violated nearly one dozen statutes and court orders, and issued guidance making it harder for U.S. Immigration and Customs Enforcement to deport people.

“Upon assuming office, he immediately went to work reversing and tearing down the effective border policies of the last two administrations, replacing them with an open borders policy,” Green said.

“What we have found thus far is damning,” he said. “To date, our investigation has discovered that (Mayorkas) has violated the laws of the United States, abused the authority of his office, and betrayed the public trust through repeated dishonest and misleading statements to Congress and the American people, while also demonstrating gross incompetence.”

Green added, “When I last checked, the United States was a nation of laws. We expect our leaders to follow the laws that Congress passes and those who fail to do so should be exposed and face the consequences.”

The top Democrat on the committee, Rep. Bennie Thompson of Mississippi, slammed the investigation and hearing as “political theater from congressional Republicans” and a “sham.”

“Calling a hearing and saying “case closed” before you’ve heard any testimony is not legitimate oversight,” Thompson said.

Thompson said Wednesday’s hearing wasn’t really about border security, nor was it even about Mayorkas or the Department of Homeland Security.

“It’s about partisan politics,” Thompson said. “It’s about House Republican leadership catering to its most extreme MAGA members who want to impeach someone, anyone at all.”

A Department of Homeland Security spokesperson said in a statement that “instead of pointing fingers and pursuing baseless attacks, Congress should work with the Department” to pass comprehensive immigration reform legislation.

“Secretary Mayorkas is proud to advance the noble mission of the Department, support its extraordinary workforce, and serve the American people,” the statement said. “The Department will continue to enforce our laws and secure our border, protect the United States from terrorism, and improve our cybersecurity, all while building a safe, orderly and humane immigration system.”

Those who spoke at Wednesday’s hearing included: Chad Wolf, former acting secretary of the U.S. Department of Homeland Security; Rodney Scott, a former Border Patrol chief; Joe Edlow, a former acting director of U.S. Citizenship and Immigration Services; and Eleanor Acer, senior director of refugee protection for the organization Human Rights First.

While Wolf, Scott and Edlow painted the Biden administration’s immigration policies as promoting “open borders” and harming national security, Acer said policies put in place under former President Donald Trump violated refugee law and “inflicted human suffering” on migrants. 

“Asylum is both morally just and politically popular,” Acer said. “The United States is more than capable of humanely receiving and fairly processing the claims of people seeking refuge here.”

NewsNation spoke to a couple border agents who recently retired.

While one of them, former San Diego Sector Patrol Agent in Charge JJ Carrell, had the option to stay, like others in his position, he chose to leave because of issues he saw on the border.

“Nothing makes sense — and it’s done on purpose,” Carrell said. “It’s intentional chaos. No one’s doing anything to stop it…Morale doesn’t exist. Guys are waiting. They’re counting down when they can retire.” 

Former Yuma Sector Chief Chris Clem, who retired in December, says it doesn’t matter if Mayorkas is impeached because the person who put him in place is still there.

Although Clem said the House GOP investigation does call attention to the problems and “holds people accountable,” he added that “as long as the same person is going to be appointing the next person — it’s just going to continue.”

NewsNation partner The Hill contributed to this report.