Federal Bureau of Investigation officials ignored warnings about the radical origins and nature of the mosque frequented by the Tsarnaev brothers for years before this April’s deadly Boston Marathon bombings.

Outgoing FBI Director Robert Mueller has also said that although the FBI visited the mosque in the past — as part of its “outreach” to the Muslim community — he was unaware of the Islamist leanings of the Islamic Society of Boston (ISB), which runs the Boston bombers’ house of worship.

But the FBI was warned nearly four years prior to the bombings that the ISB was a nest of Islamic radicalism.

On May 1, 2009 our organization, Americans for Peace and Tolerance (APT), briefed representatives of the Boston FBI office on the ISB mosques’ affiliation with Islamic extremism. Nevertheless, the FBI continues to claim it was surprised by the background of the ISB.

In a June appearance before the House Judiciary Committee, Mueller described how it took four days after the Boston Marathon bombings for his agency to canvass the Tsarnaev brothers’ controversial mosque.

After tough questioning by the highly perturbed Texas Republican Rep. Louie Gohmert, Mueller confessed that he had absolutely no idea the Tsarnaevs’ mosque was founded by Abdulrahman Alamoudi, who was convicted in 2004 of plotting with Libyan dictator Muammar Gaddafi to assassinate Saudi Crown Prince Abdullah Bin Abdul-Aziz.

But a review of the PowerPoint slides we used in our 2009 presentation confirms that we did alert FBI agents in Boston about Alamoudi and much more.

Legitimate warnings such as those we provided about ISB get ignored, however, because the Obama administration in 2011 instructed national security agencies to remove language “offensive to Muslims” from all of its reports and considerations. Agents may no longer refer to Islamic religious convictions as motives for terrorist acts. Even when suspects announce that they murdered Americans “for Allah,” the FBI can’t use that as an indication of what may be coming next.

The ISB mosque has been in damage control mode since the bombings. The ISB insisted that the mosque would have reported the Tsarnaevs to the FBI, had it been aware of any terrorist tendencies. Officials of the ISB also claim they immediately cooperated with the investigation.

In reality, however, the mosque emailed its members after the bombing, urging them to call the ACLU if contacted by the FBI and to get a lawyer before speaking to any government agent.

Alamoudi, ISB’s founder, is a poster boy for duping naive American leaders. He convinced two US Presidents — Bill Clinton and George W. Bush — that he was precisely the moderate Muslim leader they hungered for. In reality, Alamoudi was secretly filmed at a 2000 rally declaring himself to be a supporter of Hamas and Hezbollah.

By that point, Alamoudi had already tricked Clinton into allowing him to select Muslim chaplains for the Army and for American prisons. Islam is by far the fastest-growing religion in the U.S. prison system, with a Justice Department study concluding that between 30,000 and 40,o00 federal prisoners convert to Islam every year.

Anwar Kazmi, current ISB mosque executive board member and the mosque’s main spokesman, seems to be an accomplished protégé of the ISB’s founder. At a solidarity event for the mosque with Cambridge Mayor Henrietta Davis, Kazmi said of the Tsarnaevs: “What they have done is a grotesque perversion of the teachings of our faith… The Quran teaches us that whosoever kills an innocent person, it is as if he killed all of mankind.” Davis showed due reverence during the event.

Yet not long before he disavowed the Tsarnayevs’ terrorist act, at a rally held at the Boston Common gazebo, Kazmi sang a far different tune.

Kazmi was videotaped on the Boston Common urging the crowd to support a convicted Boston-area Islamic terrorist — Tarek Mehanna.

Tarek Mehanna, a son of Egyptian immigrants and a native of Sudbury, Massachusetts, was convicted of material support for Al Qaeda. According to prosecutors, he had planned to machine gun shoppers at an Attleboro shopping mall.

In online chats with his co-conspirators, Mehanna wrote that the 9/11 hijackers are heroes and Osama Bin Laden is like a father to him. After viewing a film of Iraqi terrorists tearing open a dead U.S. Marine’s rib cage and setting it on fire with gasoline, Mehanna gloated, “Heh yeah… nice juicy BBQ… Texas BBQ is the way to go.”

At the rally, Kazmi dropped the pretense that thrilled the Cambridge mayor and let loose, slandering the U.S. army with claims of atrocities in Iraq. Kazmi recommended the website FreeTarek.com, telling the crowd that he visited the site that morning and “read some of the things Tarek has written, and I was truly inspired and I’m sure that you will be inspired as well.”

Mehanna’s mother spoke at the rally and claimed that Tarek is being “persecuted for being a Muslim” and that “one day all of our kids will be in his place.” The Tsarnaev brothers’ mother has likewise claimed her sons’ innocence and accused the United States of persecuting them for being Muslim.

A young man who claimed to represent the Occupy Boston movement told the crowd: “I believe that Tarek is innocent of any wrong-doing… Tarek is an Egyptian American who empowered his community — an oppressed community, the Muslim community, speaking against U.S. wars in the Middle East. He represents in that sense a link in the chain of international solidarity against this global system that has oppressed so many of us.”

He concluded by saying, “At the end of the day, we are all Tarek Mehanna.”

The sentiments expressed by the ISB spokesman and his associates is similar to the ideas of Dzhokhar Tsarnaev, the younger and surviving Boston Marathon bomber, who left a note in the boat where he was eventually caught that expressed a visceral hatred for America, justified the bombings as revenge for U.S. wars Iraq and Afghanistan and claimed that when America attacks one Muslim, it is attacking all Muslims.

As Kazmi and others’ statements at the Boston Common show, this is a standard message that is widely taught in local mosques and openly expressed even in Boston’s most public places. Media accounts have focused on how a New England Muslim youth like Tsarnaev was radicalized by jihadist websites, but in fact these ideas were available right in his own mosque.