Congress heard horrifying testimony Tuesday about a network of assassins associated with Mexican cartels and operating in the U.S.

Mike Boudreaux, sheriff of Tulare County in California, said his agency recently dismantled the Sinaloa Cartel’s operations in his area, and part of that was the arrest of a self-admitted cartel hitman who claimed more than 25 kills in the state.

“He was responsible for certain areas of California and there were many other assassins assigned by cartels in California, throughout California, that were responsible for those areas,” the sheriff testified.

He also said in the course of his investigation, which targeted some 50 cartel associates, he was told that smuggling people, drugs and guns across the border is “easier now than in the history of their cartel.”

The revelations shocked members of the House Judiciary Committee, who wanted to know if it was a problem nationwide.

“Much of what I speak of in regards to California, the violence as well as human trafficking, it’s mirrored in other states,” Sheriff Boudreaux said.

He said the cartels seek out migrants living in small farming communities and work to control them in the same way that they control territory in Mexico.

“It’s already rooted,” he said.

He was testifying as part of a hearing featuring women whose children had died in incidents they laid at the feet of the border chaos that’s erupted under President Biden.

Among the victims were Kayla Hamilton, a 20-year-old who was raped and strangled by an illegal immigrant; Jocelyn Nungaray, a 12-year-old girl whose strangulation has been blamed on two illegal immigrants; and Rachel Morin, a mother slain on a jogging trail in Maryland.

Their mothers blamed the slayings on the Biden-Harris administration.

“I think that if we had the policies in place that we did a few years ago that vetted the immigrants that came in, my daughter would still be here,” said Patty Morin, mother of Rachel Morin.

Tammy Nobles, mother of Kayla Hamilton, said her daughter could have been saved if the government had followed the procedures for identifying gang members at the border. Instead they missed the signs and a man associated with MS-13, who came over the border as an unaccompanied alien child, has now been convicted of slaying her daughter.

“She would be alive today if they would have made that one phone call to El Salvador to check, because he did have a criminal record in 2020 and gang tattoos,” Ms. Nobles said.

Democrats on the committee said they shared the pain of the mothers, but questioned the timing of the hearing, saying it was political theater ahead of the election. The hearing took place hours before a televised debate between Vice President Kamala Harris, the Democratic nominee, and former President Donald Trump.

Rep. Veronica Escobar, Texas Democrat, said the blame on the Biden-Harris administration was misplaced and it is up to Congress to solve immigration and border issues.

“We have colleagues who are exploiting people’s pain for political purposes,” she said.

That angered April Aguirre, a crime victim advocate who has been assisting Alexis Nungary, mother of Jocelyn, the 12-year-old strangled earlier this summer.

“It’s insulting you would say that to these families,” she said. “Not one time, when her daughter was murdered and I was helping her navigate the criminal justice system, did one Democrat call me to offer their assistance. Only Republicans.”

Ms. Nobles also refuted the exploitation charge.

“I am not being forced to be here. I am here because I want to be here, I want changes to be made,” she said.

Buffeted by that response, Rep. Jerrold Nadler of New York, the top Democrat on the committee, tried a different tactic, complaining that U.S. gun laws serve as a magnet for illegal immigrants and fuel organized crime.

Rep. Glenn Ivey, Maryland Democrat, said illegal immigrant crime has been a persistent issue for years. He said that when he was a prosecutor two decades ago, he handled a brutal MS-13 murder.

Rep. Dan Bishop, North Carolina Republican, countered that the incidents of high-profile crimes seem to be increasing.

“Now we have a hearing in front of us today in which I think I counted five dead, I think I got four brutal sexual assaults, a couple of those [were] children,” he said.

Sheriff Boudreaux estimated that in his California county, 50% of the crimes for which he makes arrests involve an illegal immigrant perpetrator.

• Stephen Dinan can be reached at sdinan@washingtontimes.com.