By day, the 36-year-old Twin Cities man worked as a case manager at a community health clinic. Online, the FBI believes, he answered a call last year to work for a pro-ISIS propaganda group.

Probing the man's social media activity, agents found dozens of private messages allegedly exchanged with a suspected ISIS militant. This September, according to new court filings reviewed by the Star Tribune, the FBI stepped up its investigation and raided the man's apartment in Fridley.

But in a recent and unusual twist, his attorney has demanded that the government return a trove of property taken during the raid — including cellphones, computers and an iPad — and asked a judge to order the FBI to disclose the evidence and sources it cited to get a search warrant in the first place. The attorney, Jordan Kushner of Minneapolis, argues that the search was illegal.

The motion could set up a rare legal challenge to the FBI's series of ongoing terrorism investigations across Minnesota.

Kushner's motion argues that the FBI used the man's "exercise of his constitutionally protected First and Second Amendment" rights, rather than probable cause, to obtain the search warrant. "Further evidence would have been false," Kushner wrote.

Details of the case surfaced in court documents filed by Kushner on Monday — but then quickly sealed by a judge.

They suggest that the case could represent a fresh, and complicated, development in Minnesota's 15-year history of counterterrorism probes.

Anders Folk, a Minneapolis attorney and former federal prosecutor, said the time line of the investigation appears on par with the resource-intensive nature of terrorism cases, but added that allegations of helping with propaganda could represent a new chapter in counterterrorism investigations.

New meaning of 'support'

"That is certainly a different kind of theory of material support than what we've seen charged in Minnesota before, but not outside the types of charges we've seen brought in other jurisdictions in the U.S. and U.K.," Folk said. "The closer cases get to First Amendment protected speech, the more complicated they get — which is as it should be."

Reached by phone, Kushner declined to elaborate on what he referred to as his client's constitutional rights.

By Tuesday of last week, the motion and all other proceedings in the case were sealed. In the motion, Kushner requested that prosecutors be ordered to disclose the FBI's application to search his client's home, other "law enforcement reports and other evidence supporting the warrant."

Kushner is seeking an evidentiary hearing to determine the legality of the search and seizure of property, but it is unclear whether a judge has ruled on the motion or scheduled a hearing on the matter.

The Star Tribune first reported last month that the FBI has been investigating the man since 2016. That's when agents allegedly found private Facebook messages in which he agreed to help with English translation for a "news agency" called Dabiq, a propaganda outlet produced by the Islamic State of Iraq and Syria. The Star Tribune is not naming the man, a Fridley resident and father of four, because he has not been charged with a crime.

According to court documents reviewed by the Star Tribune, the FBI searched a Facebook account and 15 Twitter accounts belonging to the man in August 2016, finding about 48 direct messages between him and an account for "Mu'assad Sharq Afriqiya," who is believed by authorities to be a member of ISIS.

Agents also noted that the man made public Facebook posts last year that included an image of President Barack Obama being beheaded and comments that terror attacks in Paris should "be a lesson" for other countries.

On New Year's Eve 2015, the man allegedly posted an image of ISIS militants with the comment: "People of the Year. Your bravery made all of us proud in 2015." The FBI said he also "repeatedly" posted content published by the media wings of both ISIS and Al-Shabab.

Contact made

According to an FBI agent's search warrant affidavit, Afriqiya messaged the man in January 2016 and expressed joy at meeting ISIS supporters "who are working hard" and are also Somali.

"May Allah guide us to the righteous path," the man replied.

Next, Afriqiya asked about the man's English proficiency and if he followed "Dabiq news agency." The man told Afriqiya he followed the news source "very well."

"Good. So you can help us with the translation."

"Leave everything English to me."

It's unclear whether the man followed through on his offer because, the FBI says, he agreed to open a new account on an "encrypted mobile messaging application."

"We can speak freely there. And it's more secure than Facebook," Afriqiya said.

The Dabiq news agency is considered an "unofficial auxiliary" propaganda account, separate from ISIS' more structured media wing, according to Aaron Zelin, a fellow at the Washington Institute for Near East Policy. He said Dabiq is used by jihadists to push messages out to a broader audience, then amplified by supporters around the world.

"It … helps further propagate [ISIS'] message and access force multipliers," Zelin said.

'Not contraband'

The target of the FBI's probe worked until March 2017 as a case manager at a Twin Cities community health clinic. Through both his wife and attorney, the man declined to comment for this article.

The FBI and U.S. attorney's office in Minneapolis declined to comment on the investigation, citing Justice Department policy.

In his court filing, Kushner argued that his client "is aggrieved by the continued deprivation of his property." According to the motion, the government has refused to return property including multiple phones, computers, an iPad, DVDs, CDs, thumb drives, financial records, written records and other items needed "for his personal and business affairs or is otherwise entitled to have and use." The attorney said the FBI has had ample time to photograph or copy any items of interest before returning them.

"The items are not contraband and do not contain evidence of crimes," Kushner wrote.

Stephen Montemayor • 612-673-1755 Twitter: @smontemayor