The U.S. Department of Justice has opened a civil rights investigation into a New Jersey township’s denial of a Muslim group’s application to build a mosque, NJ.com reported Wednesday.

Confirmation of the investigation comes days after Bernard Township’s former mayor, Mohammed Ali Chaudry, and the Islamic Society of Basking Ridge (ISBR) filed a lawsuit against the township and 15 planning board members alleging that their decision to deny the application was motivated by Islamophobia.

The suit alleges that Bernard Township planning board members were swayed by a swell of local opposition to the mosque, which masked anti-Islam sentiment.

The federal investigation will attempt to determine whether the township violated Chaudry’s and other ISBR members’ constitutional right to freedom of worship, according to NJ.com.

In a statement sent to the news site, Mayor Carol Bianchi said that the township will fully cooperate with investigators.

“I know our Planning Board members and they are honest and ethical,” she said in the statement. “I trust they made their decisions based solely on land use considerations.”

Bianchi was on the planning board when the decision to reject the mosque plan came down, and is also named as a defendant in the lawsuit.

While officials in the rural township insist that construction issues like overly bright lighting and insufficient parking determined their decision, the ISBR counters that they spent $450,000 trying to accommodate the board’s land use concerns.

The group argues in the suit that their four-year battle to build a mosque was waged against a backdrop of anti-Muslim rhetoric and activities. During the months that the proceedings dragged on, flyers linking Islam to terrorism were papered throughout the town and planning board meetings were interrupted by residents asking if worshippers would use the property for animal sacrifices.

You can read the ISBR’s full lawsuit here.