Reuters/Boston

Jurors in the trial of accused Boston Marathon bomber Dzhokhar Tsarnaev were shown text messages on Monday that prosecutors say he sent to a friend shortly after the attack, saying "U saw the news?... Better not text me my friend."

FBI computer specialist Kevin Swindon said the texts came from Tsarnaev's iPhone and were sent to Dias Kadyrbayev, a school friend from the University of Massachusetts Dartmouth. Swindon said the texts were found in a backup file on Tsarnaev's laptop computer.

In testimony last week, Swindon also said copies of Al Qaeda's "Inspire" magazine were found on his laptop, including one titled "How to Make a Bomb in the Kitchen of Your Mom" and another document called "The Slicing Sword."

Defense attorneys have already admitted that the 21-year-old defendant committed all the crimes he is accused of, but they also contend Tsarnaev did so in an act of subservience to his older brother, not because of a personal passion.

Defense attorney William Fick asked Swindon whether the files he discussed in court represented a "fly speck" of data held on the laptop, which was otherwise filled with files like homework assignments and pop music clips. Swindon responded he needed a definition of "fly speck."

Tsarnaev is accused of killing three people and injuring 264 with a pair of homemade pressure-cooker bombs at the race's crowded finish line on April 15, 2013, and with fatally shooting a police officer three days later as he and his 26-year-old brother, Tamerlan, tried to flee the city.

Tamerlan died following a gunfight with police later that night and Dzhokhar was arrested after a homeowner in the suburb of Watertown found him hiding in a boat in his backyard. He left a note in that boat suggesting that the attacks were an act of retribution for U.S. military campaigns in Muslim-dominated countries and that he viewed his brother as a martyr.

Defense attorneys are focusing their efforts not on proving Tsarnaev's innocence, but on trying to spare his life by persuading the jury that Tamerlan bore the brunt of the blame.

While they opened the trial by admitting Tsarnaev's role, he has maintained his not-guilty plea, leaving prosecutors to first convince the jury of his guilt before moving on to the question of whether he should be sentenced to death or to life in prison without possibility of parole.

Swindon, the first witness to speak on Monday, the 11th day of the trial, also identified another text message from Tsarnaev's phone sent shortly after the bombing, telling Kadyrbayev he can go to Tsarnaev's dorm room and "take what you want." Kadyrbayev pleaded guilty last year to obstruction of justice for removing evidence from the room.

The bombing killed restaurant manager Krystle Campbell, 29, graduate student Lingzi Lu, 23, and 8-year-old Martin Richard. Massachusetts Institute of Technology police officer Sean Collier, 27, was shot dead three days later.