You may have thought the authenticity of President Obama’s birth certificate was confirmed once and for all in April. Perhaps you never questioned it. But for America’s first African-American president, incongruous questions and doubts about his citizenship, fostered by fiercely partisan politics and a hungry media culture, are still being raised.

Maricopa County Sheriff Joe Arpaio speaks during a visit to the Rancho Bernardo Inn. (Sandy Huffaker/Getty)

Now, Maricopa County Sheriff Joe Arpaio’s “Cold Case Posse” has been ordered to investigate the authenticity of President Obama’s birth certificate at the behest of a tea party group. Arpaio became well known for his self promotion as “America's Toughest Sheriff” and for his stance on the immigration laws in Arizona.

Arpaio told WorldNetDaily his decision to investigate Obama’s birth certificate has nothing to do with “politics.”

“My door is open to everyone, and I don't kick them out. If a complaint is legitimate, I don't dump it into the wastebasket,” he told WND. “When I get allegations brought to me by the citizens of Maricopa County, I look into the allegations, just like I am doing here.”

The complaint was brought by the Surprise Tea Party, described on their Web site as “a group of non-partisan citizens that are concerned about the direction of our country.” Brian Reilly, a spokesman for the group, said he believes the Cold Case Posse “will seek to discover the truth in the matter” of Obama’s birth certificate.

So-called “birthers” question whether Obama was actually born in the United States and is constitutionally qualified to be president. Some believe his birth certificate is a forgery and that he was born in Kenya.

In response to numerous lawsuits and rampant speculation, Obama released his detailed Hawaiian certificate of live birth in April. Dr. Chiyome Fukino, former director of the Hawaii Department of Health, told CNN she had “no doubt” that Obama was born on the island state.

Before that, Obama’s campaign released a standard birth record and newspaper announcements of his birth, the Post reported.

But none of this has alleviated the Surprise Tea Party’s doubts. A letter from the chapter explained why:

The Surprise Tea Party is concerned that no established law enforcement agency or other duly constituted government agency has conducted an investigation into the Obama birth certificate to determine if it is in fact an authentic copy of 1961 birth records on file for Barack Obama at the Hawaii Department of Health in Honolulu or whether it, or they, are forgeries.

To date, despite continuing legal challenges, the Hawaii Department of Health has refused to make public or to release to independent forensic examination by qualified examiners the original Obama birth records yet held in secret in the Hawaii Department of Health files.

The story made the front page of the tabloid The Globe. (The Globe.)

The controversial sheriff is no stranger to publicity. He’s appeared on realty shows, including “Steven Seagal Lawman,”and required his inmates to wear punk underpants.

His department is under investigation for alleged civil rights violations, the Post’s Jerry Markon reported. Still, his endorsement is being sought by GOP candidate Michele Bachmann.