The surviving Boston bomber has now confirmed to the FBI that he was influenced by Internet sermons of Anwar Awlaki, the American-born preacher who was killed in a U.S. drone strike in Yemen in September 2011. The same Anwar al Awlaki, who helped to motivate, directly or indirectly, the U.S. Army psychiatrist who killed 13 people, the young Nigerian student responsible for the Christmas Day bomb attempt, John Walker Lindh, the man known as the "American Taliban," and two of the 9/11 hijackers, Khalid al-Midhar and Nawaf al-Hazmi.
But who exactly is Anwar Awlaki and how does he still have such sway over impressionable minds?
I believe that the answers to these questions can teach policymakers on both sides of the Atlantic very valuable lessons about how to prevent radical Islamic extremist violence.
The most salient fact about al Awlaki is that for all his rhetorical and revolutionary bravado, he was not actually a Muslim scholar at all.
He studied engineering, education and human resources, but somehow never got round to Islam. When challenged about his Islamic education by a questioner on his own website, he responded that his Islamic education consisted of a few months' study here and there with various scholars, and some light reading and "contemplation." He did not claim to have any qualifications from an Islamic seat of learning, nor even claim to have any from a secular academic institution's course on Islam.
And yet, online, nothing stopped him being seen as either a scholar or as speaking for Islam. In this way, his reputation spread. He was invited to speak to student Islamic societies and radical mosques worldwide, and his videos are available online for wayward people like Tsarnaev to see.
In short, Awlaki was a fake. He was not a scholar, he was a dangerous attention seeker. He was to Islam what Terry Jones, the self-styled pastor who wanted to burn the Quran, is to Christianity. (Reportedly, Jones' only qualification is, lest we forget, an honorary degree from an unaccredited school of theology, and he was found guilty by a German court of falsely claiming the title of "doctor" in 2002.)
But this is not an isolated case. In fact, it is highly representative.
The vast majority of violent Islamists have never actually had any Islamic education either. Nearly 90 percent of violent Islamists have actually had no religious education at all. For example, none of those who carried out the 9/11 attacks on the United States or the 7/7 attacks on London had received any education in what Islam actually says about such violence.
And even al Qaeda's leadership lacks credibility. Osama bin Laden never attended a religious seminary and had no formal religious training. Most of its leaders have backgrounds in medicine, engineering or business.
And if you look at what the instigators of violence such as al Qaeda regard as the biggest threat to their influence, it is by their own accounts mainstream Islamic education.
Quite simply, they fear that their followers will look at authentic Islam, and discover that it doesn't teach violent jihad at all. The biggest danger to their long-term recruitment, motivation and longevity is the idea that young people might begin to see that authentic Islam actually condemns the violence they espouse.
And the reason that authentic Islamic education works to prevent the motivation to radicalize, is that extremist groups like al Qaeda have nobody qualified to respond.
Other countries understand this and have started to act on it. They send Islamic scholars into prisons to speak to those convicted, and show them that they have been hoodwinked by a perversion of Islam which justifies violence. The tactic of undermining the intellectual conditions which foster radicalization has been used by governments in Egypt and Yemen for many years. In these cash-strapped times, it is a way to keep us safer which is cheap or free.
The Solas Foundation in Scotland has already begun to do that in Britain and has been described by Scotland Yard as one of the most effective anti-radicalisation projects in the world. It offers genuine, authentic Islamic teachings which put the history of Islamic thought in its proper context. Rather than aiming to cure radicalization, it aims to prevent it, by quietly changing young minds to cut off the attraction of radical discourses.
It is programs like this which will solve the problem of radicalization which lie at the heart of sorry stories like that of the Tsarnaevs.
Dr Azeem Ibrahim is the Executive Chairman of The Scotland Institute and a Fellow at the Institute for Social Policy and Understanding.