Dzhokhar Tsarnaev went on trial for his life Wednesday in the Boston Marathon bombing with his own lawyer bluntly telling the jury he committed the crime. But she argued that he had fallen under the influence of his older brother.

“It WAS him,” Judy Clarke, one of the nation’s foremost death-penalty defense attorneys, said of Tsarnaev in a startling opening statement in the biggest terrorism trial in the U.S. since the Oklahoma City bombing nearly 20 years ago.

Laying out an argument aimed at saving Tsarnaev not from a guilty verdict but from the death penalty, Clarke said that the defense will not try to “sidestep” his involvement in the “senseless, horribly misguided acts carried out by two brothers.”

“The evidence will not establish and we will not argue that Tamerlan put a gun to Dzhokhar’s head or that he forced him to join in the plan,” Clarke said, “but you will hear evidence about the kind of influence that this older brother had.”

Prosecutors used their opening statements to sketch out the scene of horror at the marathon. They accused Tsarnaev of cold-bloodedly planting a bomb designed to “tear people apart and create a bloody spectacle,” and hanging out with his college buddies afterward as if nothing had happened.

“He believed that he was a soldier in a holy war against Americans,” Assistant U.S. Attorney William Weinreb said. “He also believed that by winning that victory, he had taken a step toward reaching paradise. That was his motive for committing these crimes.”

Three people were killed and more than 260 hurt when two shrapnel-packed pressure-cooker bombs exploded near the finish line on April 15, 2013. Tsarnaev, then 19, is accused of carrying out the attacks with his 26-year-old brother, Tamerlan, who was killed in a shootout and getaway attempt days later.

A shaggy-haired, goateed Tsarnaev, 21, slouched in his seat and showed no reaction as Weinreb spoke, not even when the prosecutor described how Tsarnaev ran over his brother with a stolen Mercedes and dragged the body 50 feet during the getaway.

Prosecutors contend the brothers — ethnic Chechens who arrived from Russia more than a decade ago — were driven by anger over U.S. wars in Muslim lands.

Because of the wealth of evidence against the younger brother — including a video of him leaving a backpack at the scene, and incriminating graffiti scrawled on the boat where he was captured — legal experts have said all along that there is little chance of escaping conviction.

Instead, they said, Tsarnaev’s lawyers will concentrate on saving him from a death sentence during the penalty phase of the case by arguing that Tamerlan was the driving force in the plot and that the adoring younger brother was manipulated or coerced into taking part.

Tamerlan Tsarnaev has been implicated in the grisly 2011 slayings near Boston of three men. Their throats were slit, and marijuana was scattered on their bodies.

Clarke, in an opening statement that took less than 20 minutes, ended by asking the jury to “hold your hearts and minds open” until the penalty phase.

In an apparent attempt to show that the attack was calculated for maximum carnage, prosecutors called as the trial’s first witness Thomas Grilk, executive director of the Boston Athletic Association, which oversees the 118-year-old marathon.

Grilk said that up to a half-million spectators turn out for the race each year, with people lining the streets in cities and towns along the 26.2-mile course and huge crowds near the finish line in Boston.

Then the jury was shown a video of the first explosion. It depicted a blast of smoke, police officers running toward the scene and runners looking over their shoulders.

About two dozen victims took up one entire side the courtroom Wednesday, listening somberly as Weinreb described the carnage. Several hung their heads and appeared to fight back tears.

Among those in court was Heather Abbott, who lost a leg in the attack. None of the victims came in on crutches or in wheelchairs; all appeared to walk under their own power.

Weinreb said Tsarnaev carried a bomb in a backpack, and it was “the type of bomb favored by terrorists because it’s designed to tear people apart and create a bloody spectacle.”

Sketching out the ghastly scene on the streets after the bombs blew up, the prosecutor said: “The air was filled with the smell of burning sulfur and people’s screams.”

The prosecutor described how 8-year-old Martin Richard stood on a metal barrier with other children so he could get a good view of the runners.

“The bomb tore large chunks of flesh out of Martin Richard,” and the boy bled to death on the sidewalk as his mother looked on helplessly, Weinreb told the jury, with the youngster’s parents in the courtroom.

After the bombings, Tsarnaev “acted like he didn’t have a care in the world,” the prosecutor said. Weinreb said Tsarnaev went back to the University of Massachusetts-Dartmouth and hung out with his friends.

“While victims of the bombing lay in the hospital and learned that they would have to have their limbs chopped off to save their lives, the defendant pretended that nothing had happened,” Weinreb said.

Tsarnaev’s lawyers fought right up to the last minute to have the trial moved out of Massachusetts, arguing that the emotional impact of the bombings ran too deep and too many people had personal connections to the case. Their requests were rejected by U.S. District Judge George O’Toole Jr. and a federal appeals court.

The panel of 10 women and eight men was chosen Tuesday after two long months of jury selection, interrupted repeatedly by snowstorms and the requests to move the trial, which is expected to last three to four months.

Clarke has saved a string of high-profile clients from the death penalty, including Atlanta Olympics bomber Eric Rudolph; Unabomber Ted Kaczynski; and Jared Loughner, who killed six people and gravely wounded then-Rep. Gabrielle Giffords in a 2011 shooting in Tucson, Arizona.

(AP)