Boston bombing trial: What was on Tsarnaevs' home computer?

An array of electronic devices analyzed in the Boston Marathon bombing investigation contained content from radical Muslim sources. But it's not clear who used them.

Prosecutors in the trial of accused Boston Marathon bomber Dzhokhar Tsarnaev on Thursday presented the jury with evidence from computer devices that links the defendant to radical Islam.

The contents come from dozens of different media devices recovered from crime scenes or belonging to friends and family of the Tsarnaevs – from a Sony laptop to various cellphones and iPods.

The amount of data analyzed was “voluminous,” testified Kevin Swindon, a Federal Bureau of Investigations special agent and supervisor of the bureau’s "cyber squad." One laptop contained more than 500,000 files on its hard drive.

But several files were common to different devices, and these files were closely tied to radical Islamic teachings.

There were multiple copies of Inspire Magazine, an English language magazine published by Al Qaeda in the Arabian Peninsula. Some PDF copies of the magazine dated from as early as fall 2010, and one of the Inspire articles found was titled “How to build a bomb in the basement of your Mom.”

Mr. Swindon said a number of the audio devices also included sermons from United States-born radical Muslim cleric Anwar Al-Awlaki, as well as several copies of “Nasheed” hymns v simple, memorable melodies that have become “a capella battle hymns” of global jihad, according to The Washington Post.

Not all the files related to Islam. The jury also saw a copy of Mr. Tsarnaev’s résumé from when he was a student at the University of Massachusetts at Dartmouth, what appeared to be a graduation photo, several selfies, and some homework assignments — including a term paper for a Modern World History class titled “The Predator War.”

In the grand scheme of the trial, the contents of these media devices may be important in portraying how self-radicalized Tsarnaev was. Outside experts say that Tsarnaev’s defense team will try and convince the jury that he was pressured into carrying out the bombings by his older, more radical brother, and thus doesn’t deserve the death penalty.

Despite the volume of jihadi material released in court Thursday, that argument may still not be out of reach. While Swindon was able to confirm these files existed on a variety of electronic devices, he admitted that he couldn’t determine what person downloaded the content, or who specifically viewed it and when.

A desktop computer he analyzed from the Tsarnaev’s apartment in Cambridge, Mass., for example, had multiple usernames.

“Were you able to determine if this was used by only one person, or by many people?” asked Assistant US Attorney Aloke Chakravarty.

“I think it was used by many people,” Swindon replied.

The defense team objected repeatedly throughout the day to the court admitting certain pieces of evidence. For the most part Judge George O’Toole allowed the names of the media files to be read out loud in the court.

There will be no testimony Friday. The trial will resume Monday morning, likely with a defense cross-examination of Swindon.