Opponents of Gov. Scott Walker said they have faced threats and thefts in the days since the recall effort began.
Two volunteers in the petition drive reported violent threats made against them to the police. Neighbors in Monona also complained to authorities of politically motivated thefts from their yards.
The threats involved phone calls from an area code in Minnesota. The calls came overnight after Walker's opponents began the recall, said Madison resident Tom Peer, who said he received a call at 2 a.m. on Thursday.
"They said, 'If you don't stop circulating recall petitions, we will kill you,'" said Peer.
A similar call came to Heather DuBois Bourenane, of Sun Prairie. The United Wisconsin recall worker jumped out of bed when her phone rang around 4 a.m. on Thursday.
"He said I had attracted the attention of some very bad people, and my life and the lives of my family were in danger," Bourenane said.
She called Sun Prairie police, who confirmed investigators were working on the case.
The male voice's number came from the Minneapolis area. WISC-TV called that number Sunday, but the calls went straight to voicemail and the message service hadn't been activated.
Meanwhile, neighbors on Dean Avenue in Monona said they had contacted police that someone had stolen several political signs from their yards.
Jim Lemens had three signs taken since the recall began Tuesday. On Sunday, another large homemade sign sat in his front yard.
"I can't just give this up. If it wasn't important to me, I wouldn't have put the sign up in the first place," Lemens said. "It's just sad, it's not how things are supposed to be around here. It's not what Wisconsin's known for."
Police had been driving by more often since the incidents, but they keep happening, Lemens said. Monona Police declined comment until Monday.
"It's just uncomfortable, you just don't want to live in an area where you constantly have to watch out the window," Lemens said, adding that another neighbor was considering pouring concrete to protect his sign. "I'm just a guy with a sign. I'm not intimidating anybody, I'm not forcing anybody to do anything they don't want to do."
Police have reminded people that acts such as stealing yard signs, making threats, and ripping or falsifying recall signatures constituted crimes.
The United Wisconsin recall effort had gotten 105,000 signatures by Saturday, the group reported.
"Ninety-nine percent of the people who drive by or people who come up to our petition centers are very polite and very kind," DuBois Bourenane said. "But every now and then you have someone who wishes we weren't there and has something to say about it."
Peer, the recall volunteer helping with signatures on Madison's east side, said most of his interactions this week had been positive.
"Mostly, I'm getting a lot of honks and waves from people who've already signed," he said. "Others, they sign up and they say, 'Thanks for being out here.'"
"I'm a peaceful guy. I don't want any violence or any negative actions out of what's going on in our political situation."