A year before the 2013 Boston Marathon bombing, on the day of the 2012 race, Dzhokhar Tsarnaev posted on Twitter what now seems to be an ominous warning.
"They will spend their money, and they will regret it and then they will be defeated," he wrote on April 16, 2012.
He was quoting Anwar al-Awlaki, the American-born Al Qaeda propagandist, a prosecution witness testified Monday, in a chilling foreshadowing of what was to come.
The source of the quote was revealed for the first time in the trial Monday, during testimony from Matthew Levitt, a counterterrorism expert who is a former analyst for the FBI and the US Treasury.
Tsarnaev and his older brother, Tamerlan, were probably inspired by Awlaki and other militant propagandists to cause violence in the name of Islam when they set off the bombs at the Marathon finish line on April 15, 2013, according to Levitt. Though he has pleaded not guilty, Tsarnaev has admitted his role in the explosions that killed three and injured hundreds. His brother was later killed during a violent confrontation with police.
Levitt's testimony was critical for prosecutors to show that Tsarnaev not only carried out the attacks, but he had a motive, and a message.
"That's what makes it terrorism, and not just murder," Levitt testified. "Terrorism targets civilians to achieve some type of political goal."
For roughly three hours Monday, federal prosecutors used Levitt's testimony to explain to jurors the US government's growing concerns over homegrown terrorists and to provide a motive for Tsarnaev's participation in the attack.
Levitt used Tsarnaev's own writing to demonstrate that the teenager was inspired by Al Qaeda propaganda — including on his computer and other electronic devices — and that Tsarnaev saw it as justification for his role in the Marathon bombings.
Much of Levitt's testimony focused on what prosecutors have characterized as Tsarnaev's confession: a note written in pencil on the inside of a boat in Watertown.
"The audience is the American public," said Levitt, who now works for the Washington Institute for Near East Policy and has researched and written about terrorism and the radicalization of terrorists.
"This is an attempt," Levitt testified, "to explain what's been done."
For instance, said Levitt, who holds a doctorate from Tufts University, Tsarnaev's statement that he was jealous of his brother and his request for Allah to make him a martyr was similar to the teachings of Abdullah Azzam, considered the father of modern jihad. Azzam was a Palestinian who helped fight the Soviet Union's occupation of Afghanistan. In "Join the Caravan," a text that was found on Tsarnaev's computer, he wrote that it was a Muslim's duty to take action, and that by doing so he could enter paradise, or heaven.
Levitt said Tsarnaev's declaration in the confession that, "As a Muslim, I can't stand to see such evil go unpunished," and his contention that, "We are promised victory, and we will surely get it," were also seemingly influenced by Awlaki as well as by Inspire, a magazine published by Al Qaeda in the Arabian Peninsula.
"It is about time Muslims wake up and pay America what is due to it," said one writer in Inspire magazine.
Tsarnaev had written in the boat, just before his capture on April 19, 2013, that "We Muslims are one body, you hurt one you hurt us all.
"Know you are fighting men who look into the barrel of your gun and see heaven."
Levitt said it was a reference to "the idea of not fearing death."
Tsarnaev faces the possibility of the death penalty; his lawyers have sought to use his trial to show that his older brother was the mastermind of the Marathon bombing and was a domineering influence over their client.
By showing that Tsarnaev is less responsible for the bombing, they hope to persuade the jury to spare him from a death sentence.
But prosecution witnesses have detailed a collection of Islamic militant propaganda that date back to at least January 2012 on Tsarnaev's computer and other electronic devices such as phones, iPods, and thumb drives. That would mean that Tsarnaev had access to the materials well before the Marathon bombing, contradicting the defense theory that he was quickly radicalized through the influence of his brother.
FBI supervisory agent Kevin Swindon acknowledged under defense questioning Monday, however, that he could not say who downloaded the materials and that people other than Tsarnaev had access to the electronic devices.
He also acknowledged that prosecutors only showed jurors a fraction – a defense lawyer called it "three ten-thousandths of 1 percent" – of all the materials on Tsarnaev's devices.
Defense attorneys accused prosecutors of cherry-picking the messages of a rambling teenager who spent most of his time online on Facebook. The day of the 2012 Marathon, he also wrote, "Hmmm get breakfast or go back to sleep, this is always a tough one."
Levitt testified that the selected collection of propaganda on Tsarnaev's computer was urging violence. As an example, he said, some of the musical chants common in Islamic culture, or Nasheeds, that were on Tsarnaev's iPods celebrated jihad, and had voice-overs of Awlaki's lectures.
Levitt said that the concept of a global jihad — or a movement of like-minded Muslims to "unite as a nation" with the use of violence — has evolved over the last decade with the spread of online propaganda and the growth of social media.
He also said it has been hijacked by an extreme wing of the religious community who seek to do harm "in the name of Islam."
Levitt is slated to continue his testimony on Tuesday.