By Tim Gaynor
PHOENIX (Reuters) - A tough-talking Arizona sheriff, already embroiled in a Justice Department bias investigation and other woes, waded deeper into controversy on Thursday with an attention-grabbing 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 valley.
The White House has had to deny 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 the speculation within some Republican circles that he was not born in the United States.
"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," Maricopa County Sheriff Joe Arpaio told a news conference.
Arizona Democratic Party finance director Dan Mitchell later sent out an e-mail on Thursday seeking to parlay the sheriff's claims 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 press conference that instead directed readers to the opening credits of the X-Files, a 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.
The sheriff's office presented six videos which it said raised doubts about the authenticity of the date stamp on Obama's birth certificate and Selective Service Registration Card, among other issues.
JUSTICE DEPARTMENT PROBE
Arpaio's accusations come as he is under investigation by the 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.
It found Arpaio's deputies regularly made unlawful stops and arrests of Latinos and that there was evidence they used excessive force and failed to adequately protect the Hispanic community.
Arpaio told reporters on Thursday that 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.
"It has nothing to do with politics ...I said from the beginning I want the truth ... I don't care where it falls. In fact if we can prove ... that birth certificate was real, he was born here, I would be very happy with that, but we have obstacles here," he said.
The Justice Department's findings critical of Arpaio stem from an investigation that began in 2008 during the administration of former President George W. Bush. Arpaio still faces a criminal probe.
Last December, a federal judge barred Arpaio from detaining people simply because they were in the country illegally and sanctioned the sheriff for destroying related documents.
Arpaio has also come under fire from critics who claim he failed to adequately investigate hundreds of sex-crimes in Maricopa County, which covers the metro Phoenix area.
Locally, Arpaio's aggressive pursuit of illegal immigrants has earned him accolades in conservative political circles. Late last year he endorsed Texas governor Rick Perry in his failed bid for the Republican presidential nomination.
(Additional reporting by David Schwartz; Editing by Cynthia Johnston and Peter Bohan)