Tarrant County Justice of the Peace Russ Casey forged voters' signatures on a petition to get on the ballot for re-election, his challenger said Tuesday.
"Voters have been defrauded," said Colleyville businessman Lenny Lopez. "We need to make sure we hold everyone accountable."
Casey declined to comment on the allegation.
Lopez and a government watchdog group claim they have signed statements from more than 30 voters who say their signatures were forged.
Lopez said he noticed a number of suspicious signatures when he obtained Casey's petition on Friday.
"They were actually all the same," he said. "It looked like reading a book someone wrote by hand."
Lopez took his concerns to Aaron Harris, of Direct Action Texas, a non-profit government watchdog.
"I've done quite a bit of work in voter fraud and specifically mail ballot fraud, so we look at a lot of signatures and immediately I saw a pattern," Harris said. "It looked suspicious."
Harris, along with the Lopez and Lopez's lawyer, said they contacted voters whose signatures were on Casey's petition.
"Immediately, they looked at it and said, 'This is not my signature,'" Harris said.
NBC 5 tracked down one of the voters, 73-year-old retired mechanic Robert Short, of Bedford.
He said his signature looks nothing like what appears on Casey's petition.
"It's my name but not my signature," he said. "I haven't signed a petition in a long time. I would have remembered this one."
Lopez's attorney, Alex Kim, said he is surprised by what they discovered.
"We're up to almost 70 doors knocked, and there's only two people with valid signatures," he said. "I'm sure there's some legit signatures in there. The problem is the lion's share of these are unauthentic."
Lopez is now calling for a criminal investigation.
"Honestly, I'm a stickler for law, and I think this should be prosecuted," he said.
Casey needed 250 valid signatures to get on the ballot and presented more than 300. Lopez said he is continuing to contact voters to obtain more sworn statements.
Tarrant County Republican Party Chairman Tim O'Hare said he is considering removing Casey from the ballot.
Casey's other opponent, airline pilot Bill Brandt, of Southlake, said the allegations are concerning.
"I'm looking forward to the election contest with or without Mr. Casey on the ballot," he said. "Obviously fraud is a serious charge."
Brandt said he had no personal knowledge of any alleged fraud.
Casey decided to run for re-election despite a sexual harassment scandal with a former clerk, who claimed in a lawsuit that the two had had a sexual relationship at work and that he tried to fire her soon after she told him she wanted to end it.
Casey settled the lawsuit out of court but he was publicly reprimanded by the Texas Commission on Judicial Conduct.