CHICAGO (CBS) — With DuPage County Sheriff John Zaruba retiring after more than two decades, two members of his staff are seeking their party’s nomination in the upcoming Republican primary.

The candidates are Undersheriff Frank Bibbiano and patrol Cmdr. James Mendrick. Both have worked their way up the corporate ladder.

“I’ve been with the agency about 22 years. I’ve done every job from deputy all through the ranks up to administrative bureau chief,” Mendrick said. “I’m the only candidate that’s actually been a commander patrol on the street.”

Bibbiano retorted, “I started 19 years ago as a corrections deputy — I worked in the jail. I strongly believe that an ethical campaign will definitely prevail.”

As the two go head-to-head, dirty campaign tricks have been reported in DuPage County.

Mendrick said he’s recovered over 200 vandalized campaign yard signs. Additionally, he recently discovered a damaged campaign billboard up at Route 83 and Irving Park Road in Bensenville,  which is behind a secured area. Mendrick said someone climbed 50 feet and vandalized it, adding that police are investigating.

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James Mendrick’s vandalized campaign billboard. (Photo: James Mendrick)

The billboard has since been repaired, but Mendrick points to his opponent for answers.

“I just don’t know who else would have the motivation to be harming our signs and our campaign,” he said.

Bibbiano responded, saying, “I’m a police officer. I value the law and I value people’s property. Nobody in my campaign, nor have I, vandalized anybody’s property.

“And I think the bigger issue in all of this is how he’s choosing to fund his campaign. He’s taking money from people with criminal backgrounds,” Bibbiano said, referring to Mendrick’s campaign donors. Records show Mendrick received money from a man convicted of a misdemeanor sex crime. Zaruba has received money from the same donor in previous campaigns.

“This person was somebody the sheriff introduced me to during his campaigns — said he vouched for him,” Mendrick said.

“It’s offensive to every police officer out there faithfully doing his or her duty,” Bibbiano said.

Zaruba originally endorsed Mendrick, but then switched his support and is now behind Bibbiano, donating over $50,000 to his campaign.