The three connected to the bombings and a fourth IL man were arrested on Tuesday morning and charged with possession of a machine gun.
In a written statement, the USA attorney's office in Springfield said the men - identified as Michael B. Hari, 47, Joe Morris, 22, and Michael McWhorter, 29 - also face charges of possession of assault rifles, which are classified as machine guns, and attempting to bomb an IL abortion clinic in November. No one at the Minnesota mosque was injured, but the building sustained minor damage.
According to the affidavit, Mr. McWhorter told a law enforcement official that during the attempted bombing at the Women's Heath Practice in Champaign, Ill., Mr. Morris had been dropped off at the clinic in the middle of the night, smashed the clinic window and thrown an explosive device inside.
The three suspects were arrested by Federal Bureau of Investigation agents in IL and also charged with possession of machine guns.
Tuesday, search warrants were executed at Hari's parents' home, in Paxton; a store/office owned by Hari, at 100 South Main Road, in Clarence. Hari was arrested as he was traveling to a court appearance in Ford County on unrelated assault charges.
He also said it was Hari's idea to target a mosque, with the intention to "scare them out of the country". Morris also told the source that Hari said he would pay Morris and McWhorter $18,000 for their involvement.More news: BJP adds dramatic twist to Rajya Sabha elections by adding fourth candidate
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The second informant told police that Hari detailed the mosque bombing.
Anti-Muslim incidents rose sharply in the United States in the year after the 2016 US presidential election, according to a review by the Council on American-Islamic Relations.
In announcing the charges against the men, interim U.S. Attorney Gregory Brooker described the bombing as a "tragedy for all Minnesotans".
The Dar al-Farooq mosque mainly serves Somalis in the Minneapolis area. Minnesota is home to an estimated 57,000 Somalis, the largest Somali population outside of east Africa, according to the MN State Demographic Center.
Officials said at the time that witnesses saw someone throw something from a truck or van before the blast and saw a vehicle speed away afterward.
Mohamed Omar, the center's executive director, said at the time that the mosque didn't receive any threats beforehand or claims of responsibility afterward. Mosque leaders later released security video from inside the mosque that caught the moments before the explosion, and some smoke and flying debris.