A police raid to learn who was behind a Twitter account that mocked an Illinois mayor has so far resulted in one arrest, but officials said Monday the investigation continues, as free speech advocates express concern.

The account -- @Peoriamayor -- was created about nine weeks ago and had about 50 parody tweets, mostly about Peoria Mayor Jim Ardis supposedly using illegal drugs and associating with prostitutes, before Twitter suspended it in mid-March.

The account, which had only about 50 followers, was marked as a parody roughly a week before being suspended. But Peoria police took matters a step further on April 15 by executing a search warrant at the home of a suspect, whom they believed was unlawfully trying to impersonate a public official.

The Star Journal of Peoria reports the warrant and raid were ordered by Ardis, who is now facing a public backlash, largely on social media and in editorial pages where he is being accused of trying to step on First Amendment rights.

A resident of the home told the newspaper that police seized computers and smart phones in the raid, in an apparent attempt to learn who was behind the Twitter account.

The crime is a misdemeanor punishable by a maximum $2,500 fine and one year in jail.

Three people at the home during the raid were taken to a police station for questioning. Two other occupants were visited at their workplace, then taken in for questioning.

A Peoria Police Department spokesman confirmed to FoxNews.com that one resident was charged in connection with possession of marijuana and drug paraphernalia. However, the investigation is ongoing, which prevents officials from discussing whether police will make additional arrests, he said.

“I find it very troubling,” said Angela Campbell, a professor at Georgetown University Law School. “It chills people’s First Amendment rights to criticize officials … whether it’s through parody or just calling somebody a jerk.”

Campbell, a First Amendment specialist, also questioned whether the charge of unlawfully impersonating a public official applies, since its intent is stop somebody from, for example, posing as a police officer to extract money or sex in exchange for ignoring a traffic violation.

Aaron Caplan, a professor at Loyola Law School in Los Angeles, raised similar concernsabout free speech and the impersonation issue.

“This absolutely raises concerns for me,” he said. “Under the Constitution, you can criticize people in power. It’s how you can tell the difference between a democracy and a police state. And you can do it through humor.”



However, he also has concerns about First Amendment retaliation and Fourth Amendment issues regarding the search warrant.

Caplan says executing a search warrant is unusual in the case of a misdemeanor, although he is not an expert on Illinois state law.

“I need more facts, but it smells a little like retaliation,” he said.

Peoria Police Chief Steve Settingsgaard told the newspaper the intent of the account, which also included tweets about Toronto Mayor Rob Ford, was not clearly identified as satire.

“In fact it appears that someone went to great lengths to make it appear it was actually from the mayor,” he said.