Federal officials shared a post on social media last weekend that wrongly accused a Connecticut state lawmaker of publishing detailed location information about deportation efforts by the Immigration and Customs Enforcement agency, triggering a torrent of harassment against him.

The lawmaker, Corey P. Paris, of Stamford, said that he had received threats against his life and his relatives. A spokesman with the Connecticut Department of Emergency Services and Public Protection said the State Police were investigating the incident.

In a message posted on Instagram, Mr. Paris, a Democrat, told followers on Friday that he had learned of immigration enforcement efforts in his district and wanted to warn residents to “remain vigilant.”

The influential right-wing account Libs of TikTok then shared his post on X, claiming that he was “doxxing ICE’s live location” and “helping illegals evade arrest and impeding ICE,” even though Mr. Paris had not named any specific places where agents had been seen. The lawmaker said in an interview that he has never shared exact locations of ICE activity.

The Libs of TikTok post tagged ICE’s official account and urged the agency to “charge him,” referring to Mr. Paris. ICE officials republished the post the next day and tagged the Justice Department’s account.

“When ICE re-shared that post, it didn’t just validate misinformation; it legitimized dangerous rhetoric that put my safety at risk,” Mr. Paris said. “And federal agencies should not be in the business, quite frankly, of targeting elected officials for speaking up about community safety. That’s our job.”

Mr. Paris, who is Black, said that among the threats he received was a phone call from an unidentified man who delivered a tirade laden with profanity, homophobic slurs and racial epithets and who claimed to know where his relatives lived.

In an email, Tricia McLaughlin, a spokeswoman for the Department of Homeland Security, did not respond to a question about Mr. Paris’s safety concerns, instead pointing to an increase in harassment against ICE agents. On Thursday, ICE officials evacuated an office building in Lower Manhattan after receiving envelopes containing white powder. Police officials said that the powder was found not to be hazardous.

When asked why ICE’s account had republished the Libs of TikTok post, Ms. McLaughlin said, “We frequently share posts from groups outside of government.”

In a statement, a Justice Department spokeswoman said that the agency “will not tolerate actions that disclose the location of our law enforcement and allow illegal aliens to evade capture.”

The Libs of TikTok account did not respond to questions regarding its post about Mr. Paris.

Other people singled out by Libs of TikTok have been threatened with violence, often through bomb threats, according to an investigation last year by NBC News.

In Arizona, a Democratic state senator faced death threats and calls for her expulsion from office after being targeted by the account. Like Mr. Paris, the senator, Analise Ortiz, had shared information in social media posts about sightings of immigration enforcement agents.

Ms. Ortiz and Mr. Paris both said they wanted to help residents avoid potentially dangerous encounters with ICE. Some immigrants have died while fleeing officials, and the agency has arrested U.S. citizens and legal permanent residents by mistake.

As President Trump has expanded his immigration crackdown, administration officials have asserted that so-called sanctuary laws in Democrat-led cities — which prevent local law enforcement agencies from cooperating with federal immigration officials — have undermined their efforts to detain and deport people who entered the United States illegally.

Ten miles from Stamford, the police and mayor in Norwalk, Conn., released a statement on Friday saying that city officials told ICE agents to leave when they showed up at police headquarters.

“Serious concerns have been expressed by city officials and the community regarding tactics utilized by ICE officers, including the use of face masks, plain clothes, and unmarked vehicles, a stark contrast from the transparency and accountability traditionally practiced by the Norwalk Police Department,” they wrote.

On Tuesday, Caroline Simmons, the mayor of Stamford, and Timothy Shaw, the police chief, wrote in a similar statement on Instagram that the city had experienced a spike in deportation attempts by ICE, including courthouse arrests. They said that the local police was not helping ICE with detentions, except in cases involving serious crimes.

“The recent activity by ICE officials does not align with our commitment to ensuring that all residents are treated with dignity and respect — regardless of immigration status or background,” they wrote.