PHOENIX A tough-talking Arizona sheriff, already embroiled in a Justice Department bias investigation, waded deeper into controversy on Thursday with an assertion that a probe by his office found President Barack Obama's birth certificate was a forgery.
Most Republican critics of Obama have given up pursuing such widely discredited "birther" allegations. But the investigation by Maricopa County Sheriff Joe Arpaio, carried out by what he described as five-member volunteer "posse," was prompted by a request last August from a group of conservative Tea Party activists in the Phoenix area.
The White House has denied repeated claims that Obama was not born in the United States. In April 2011, Obama released a longer version of his birth certificate to try to put to rest speculation within some Republican circles that he was not born in the country as required by the U.S. Constitution to become president.
"A 6-month-long investigation conducted by my cold case posse has led me to believe there is probably cause to believe that President Barack Obama's long-form birth certificate ... is a computer-generated fraud," Arpaio told a news conference.
Arizona Democratic Party finance director Dan Mitchell later sent out an email seeking to parlay the sheriff's charges into cash donations for the party.
"Stop the ridiculous Tea Party, birther, GOP nonsense, click here to make a donation to the Democratic Party now," the message read.
Obama campaign spokesman Ben LaBolt poked fun at Arpaio on Twitter, providing what he described as a link to a video feed of the news conference that instead directed readers to the opening credits of "The X-Files," a TV show about paranormal activity.
Arpaio, a conservative Republican who styles himself as "America's toughest sheriff," called for the U.S. Congress to investigate his findings, which concluded that forgers committed two crimes, first in creating a fraudulent document and then in fraudulently presenting it to the public.
"I want to make this perfectly clear. I am not accusing the sitting president of the United States of committing a crime. But there remain a lot of questions which beg for answers and we intend to move forward with this investigation in pursuit of those answers," Arpaio said.
Arpaio's accusations come as he undergoes investigation by the U.S. Justice Department over what it says is his widespread discrimination against Latinos.
In December, the Justice Department said Arpaio and his deputies violated U.S. civil rights laws by engaging in racial profiling of Latinos and making unlawful arrests in their bid to crack down on illegal immigrants.
Arpaio told reporters on Thursday his review of Obama's birth certificate began in August, months before the Justice Department investigation findings in December, and denied that it was politically motivated.
(Additional reporting by David Schwartz; Editing by Cynthia Johnston and Eric Walsh)