A 57-year-old Minneapolis man pleaded guilty Wednesday to a federal hate crime in connection with a bomb threat he mailed last year to a mosque that was under construction near his home.

Daniel George Fisher had admitted to FBI agents earlier this year that he sent the threatening note to the Tawfiq Islamic Center, which was building a new facility in south Minneapolis, because he was upset about its addition to his neighborhood.

Staff at the Islamic center, which primarily serves the Twin Cities' large Oromo population, received an anonymous handwritten note in September 2015 that threatened to "blow up your building with all you immigrants in it."

Fisher did not sign the note, he later told agents, because he wanted Tawfiq's staff to think that anyone in the neighborhood might want to see the mosque attacked. Fisher confessed to authorities after the FBI traced his fingerprints found on the letter.

Fisher now faces up to 20 years in prison for "obstructing, by threat of force, the free exercise of religious beliefs."

FBI special agent in charge Richard Thornton said Wednesday that Fisher's plea affirms that federal law enforcement authorities will not tolerate hate crimes. The FBI and the local U.S. attorney's office have participated in a series of community forums to discuss hate crimes.

Crimes targeting Muslims in Minnesota, and nationally, have climbed to rates unsurpassed since the aftermath of the 9/11 attacks, according to researchers and data reviewed by the Star Tribune.

"Threatening to blow up a mosque is simply un-American," U.S. Attorney Andrew Luger said Wednesday. "It is a bedrock principle of our country, enshrined in the First Amendment to the Constitution, that all people are free to practice their religion of choice."

The case was also prosecuted by the Justice Department's civil rights division.

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