Watch birther Joe Arpaio get flummoxed by CNN's simple questions: 'I'm not stupid enough to talk to you'
CNN's Jake Tapper speaks to Sheriff Joe Arpaio (screen grab)

Maricopa County, Arizona Sheriff Joe Arpaio insisted on Thursday that President Barack Obama had used forged documents for proof of U.S. citizenship, but he told CNN's Jake Tapper that he was not "stupid enough" to answer questions about the claim.

During an interview on CNN, Tapper pointed out that Arpaio and Republican presidential candidate Donald Trump shared the so-called "birther" belief that the president had lied about his birth certificate.

"You have both trafficked in this rather preposterous notion that President Obama was not born in the United States, and that he may have forged his birth certificate that he released," Tapper noted. "Why would you risk your credibility on issues that you care about -- like illegal immigration, like law enforcement -- by getting involved in this?"

Arpaio immediately took exception to the question.

"What do you mean risk?" the sheriff shot back. "I'm the chief law enforcement elected by the people. I have a right to investigate and speak out."

"We're working on a fraudulent, forged government document!" Arpaio continued, speaking in an aggressive tone. "That's what we are doing."

"You're maintaining that the birth certificate that the president of the United States revealed, you're maintaining that is fraudulent?" Tapper pressed.

"That's right," Arpaio stated.

"Is there anyone -- any credible law enforcement person outside of you and your organization, your contractors who has any agreement with you on this?" Tapper wondered.

"No, they haven't looked at it," Arpaio said defensively. "What are you kidding? I'm probably the only law enforcement official that has looked into it. Nobody looks into it. They shy away from it."

"Because the president was born in Hawaii," the CNN host interrupted.

"I don't care where he was born," Arpaio replied. "I'm talking about a fraudulent government document, a birth certificate."

"And you say that because there are glitches in some of the printing?" Tapper asked.

Arpaio, however, said he would not "get into all the technical details" because he only owned a typewriter and employed experts who knew about using computers to forge documents.

"I've been around a long time. I'm not stupid enough to even talk to you about it," he quipped.

Watch the video below from CNN, broadcast July 23, 2015.