Birkhead testified Wednesday at a Senate hearing on sanctuary city policies.
He declared Durham is not a sanctuary county.
There were tense moments in an exchange with Republican Sen. John Kennedy, of Louisiana, who questioned Birkhead, a Democrat, on his immigration stance.
Kennedy pressed Birkhead's handling of Mexican national and alleged gang member Carlos Mendoza-Martinez, who was convicted of manslaughter in Durham and released after serving prison time.
At the hearing, Birkhead testified, "ICE was notified that they could come pick up the individual, and for some reason they did not."
Kennedy told Birkhead during the hearing, "You ought to be ashamed of that," and also posed the question, "Do you need some water? Because I think your pants are on fire."
"Contrary to what the senator said, my pants were not on fire. I was as cool as I always am under fire," said Birkhead.
He called current immigration efforts "disturbing."
"It infuriates me. That's not law enforcement, and I really get upset when they refer to themselves as law enforcement officers. That's not the way we are trained. That's not the way we service our community or serve our community," said Birkhead. "And so, these tactics, in my opinion and based on my training, are illegal."
ABC11 asked about ICE arrests and detainers and whether they have waned since the beginning of Operation Charlotte's Web.
"We don't see the numbers that we saw four months ago, five months ago," said Birkhead. "I'm not seeing an uptick at the moment. I think (ICE) they've got their hands full with TSA and other jurisdictions. I think that's a fair assessment that say those numbers have gone down."
The sheriff also said he hasn't seen a significant increase in ICE detainers at the jail, but stands ready to enforce the law.
"If we have individuals who are living in North Carolina, who are documented or undocumented, and they break the law, particularly in Durham County, we're going to hold them accountable," said Birkhead.