BOSTON — Boston Marathon bombing suspect Dzhokhar Tsarnaev texted a friend 90 minutes after the deadly explosions and said, “Don’t go thinking it’s me,” a federal prosecutor told jurors Monday during opening statements at the friend’s obstruction trial.

Assistant U.S. Attorney Stephanie Siegmann also revealed that a month before the bombings, Tsarnaev told the friend, Azamat Tazhayakov, and another pal that “it was good to die” a martyr because you would die “with a smile on your face and go straight to heaven.”

Tazhayakov has pleaded not guilty to obstruction of justice and conspiracy charges. He and his roommate, Dias Kadyrbayev, went to Tsarnaev’s University of Massachusetts-Dartmouth dorm room several days after the bombing and removed a backpack, fireworks that had been emptied of their black powder and a laptop computer, prosecutors say.

Tazhayakov’s defense lawyer told jurors that his client isn’t a terrorist and never intended to help Tsarnaev. The attorney, Nicholas Wooldridge, told the jury that Tazhayakov “never even touched that bag” and never agreed to throw it away. He said Kadyrbayev took the backpack and threw it away.

Tsarnaev is accused of working with his now-dead brother to place two bombs near the finish line of the 2013 marathon, killing three people and injured more than 260. His trial is scheduled for November.

Kadyrbayev faces his own trial in September. Investigators said Tazhayakov agreed with the plan to get rid of the backpack but that Kadyrbayev threw it away. A third college friend, Robel Phillipos, is accused of lying to authorities.