BOSTON -- Dzhokhar Tsarnaev was convicted on all charges Wednesday in the Boston Marathon bombing by a federal jury that now must decide whether the 21-year-old former college student should be executed.

Tsarnaev folded his arms, fidgeted and looked down at the defense table as he listened to one guilty verdict after another on all 30 counts against him, including conspiracy and deadly use of a weapon of mass destruction. Seventeen of those counts are punishable by death.

ABC News: Marathon bombing coverage ABC News has in-depth reaction to the conviction of Dzhkohar Tsarnaev, the Boston Marathon bomber who now faces the death penalty. Coverage

The verdict -- reached after a day and a half of deliberations -- was practically a foregone conclusion, given his attorney's startling admission during opening statements that Tsarnaev carried out the attack with his now-dead older brother, Tamerlan.

The two shrapnel-packed pressure-cooker bombs that exploded near the finish line on April 15, 2013, killed three spectators and wounded more than 260 other people, turning the traditionally celebratory homestretch of the world-famous race into a scene of carnage and putting the city on edge for days.

Tsarnaev was found responsible not only for those deaths but also for that of a Massachusetts Institute of Technology police officer who was shot days later.

"It's not a happy occasion, but it's something," Karen Brassard, who suffered shrapnel wounds on her legs, said outside court. "One more step behind us."

Boston Marathon bombing counts A jury on Wednesday found Boston Marathon bomber Dzhokhar Tsarnaev guilty of all 30 federal counts against him. Here are the charges:

• Conspiracy to use a weapon of mass destruction resulting in death.

• Use of a weapon of mass destruction resulting in death; aiding and abetting (two counts).

• Possession and use of a firearm during and in relation to a crime of violence resulting in death; aiding and abetting (nine counts).

• Conspiracy to bomb a place of public use resulting in death.

• Bombing of a place of public use resulting in death; aiding and abetting (two counts).

• Conspiracy to maliciously destroy property resulting in personal injury and death.

• Malicious destruction of property resulting in personal injury and death; aiding and abetting (two counts).

• Carjacking resulting in serious bodily injury; aiding and abetting.

• Possession and use of a firearm during and in relation to a crime of violence; aiding and abetting (six counts).

• Interference with commerce by threats and violence; aiding and abetting.

• Use of a weapon of mass destruction; aiding and abetting (four counts).

She said Tsarnaev appeared "arrogant" and uninterested during the trial, and she wasn't surprised when she saw no remorse on his face as the verdicts were read.

Reaction poured out elsewhere after the verdict was announced.

"I am thankful that this phase of the trial has come to an end and am hopeful for a swift sentencing process," Boston Mayor Marty Walsh said. "I hope today's verdict provides a small amount of closure for the survivors, families and all impacted by the violent and tragic events surrounding the 2013 Boston Marathon. The incidents of those days have forever left a mark on our city. As we remember those who lost so much, we reflect on how tragedy revealed our deepest values, and the best of who we are as a community."

Boston Red Sox designated hitter David Ortiz, who famously declared "this is our f---ing city" in the aftermath of the bombings, was somber in his reaction to the news.

"What can I tell you? That's not going to bring the people who lost their lives back, you know what I'm saying? It is what it is. What else? I'm not a judge. Whatever.

"What I said that day is how I feel. I'm an emotional person and was going through some struggle, but like I said, it's not going to bring anybody's life back. So we just have to live with the consequences."

In the trial's next phase, which could begin as early as Monday, the jury will hear evidence on whether Tsarnaev should get the death penalty or spend the rest of his life in prison. In a bid to save him from a death sentence, defense attorney Judy Clarke has argued that Tsarnaev, then 19, fell under the influence of his radicalized brother.

"If not for Tamerlan, it would not have happened," Clarke told the jury during closing arguments.

Prosecutors, however, portrayed the brothers -- ethnic Chechens who moved to the U.S. from Russia more than a decade ago -- as full partners in a plan to punish the U.S. for its wars in Muslim countries. Jihadist writings, lectures and videos were found on both their computers, though the defense argued that Tamerlan downloaded the material and sent it to his brother.

Tamerlan, 26, died when he was shot by police and run over by his brother during a chaotic getaway attempt days after the bombing.

The government called 92 witnesses over 15 days, painting a hellish scene of torn-off limbs, blood-spattered pavement, ghastly screams and the smell of sulfur and burned hair.

"What I said that day is how I feel. I'm an emotional person and was going through some struggle, but like I said it's not going to bring anybody's life back. So we just have to live with the consequences."

Survivors gave heartbreaking testimony about losing legs in the blasts or watching people die. The father of 8-year-old Martin Richard described making the agonizing decision to leave his mortally wounded son so he could get help for their 6-year-old daughter, whose leg had been blown off.

In the courtroom Wednesday, Denise Richard, the boy's mother, wiped tears from her face after the verdict. The boy's father, Bill Richard, embraced one of the prosecutors.

"It's not something that will ever be over. You'll feel it forever. It's forever a part of our life," Brassard, whose ankles and shin were injured by pieces of the bomb, said Wednesday.

In Russia, Tsarnaev's father, Anzor Tsarnaev, told The Associated Press in recent days that he would have no comment.

The others killed in the bombing were Lingzi Lu, a 23-year-old Chinese graduate student at Boston University, and Krystle Campbell, a 29-year-old restaurant manager. MIT police officer Sean Collier was shot to death at close range days later.

"Sean Collier gave his life doing what he was born to do -- serving and protecting all of us as a police officer," Collier's family said Wednesday. "Sean was more than a police officer to us, though. He was a caring, fun, loyal, and protective brother and son. While today's verdict can never bring Sean back, we are thankful that Dzhokhar Tsarnaev will be held accountable for the evil that he brought to so many families. ... The strength and bond that everyone has shown during these last two years proves that if these terrorists thought that they would somehow strike fear in the hearts of people, they monumentally failed."

Some of the most damning evidence included video showing Tsarnaev planting a backpack containing one of the bombs near where the 8-year-old boy was standing, and incriminating statements scrawled inside the dry-docked boat where a wounded and bleeding Tsarnaev was captured days after the tragedy.

"Stop killing our innocent people and we will stop," he wrote.

Tsarnaev's lawyers barely cross-examined the government's witnesses and called just four people to the stand over less than two days, all in an effort to portray the older brother as the guiding force in the plot. Witnesses testified about phone records that showed Dzhokhar was at the University of Massachusetts-Dartmouth while his brother was buying bomb components, including pressure cookers and BBs.

A forensics expert said Tamerlan's computer showed search terms such as "detonator" and "transmitter and receiver," while Dzhokhar was largely spending time on Facebook and other social media sites. And an FBI investigator said Tamerlan's fingerprints -- but not Dzhokhar's -- were found on pieces of the two bombs.

Clarke is one of the nation's foremost death-penalty specialists and has kept other high-profile defendants off death row. She saved the lives of Unabomber Ted Kaczynski and Susan Smith, the South Carolina woman who drowned her two children in a lake in 1994.

Tsarnaev's lawyers tried repeatedly to get the trial moved out of Boston because of the heavy publicity and the widespread trauma. But opposition to capital punishment is strong in Massachusetts, which abolished its state death penalty in 1984, and some polls have suggested a majority of Bostonians do not want to see Tsarnaev sentenced to death.

The 12-member jury must be unanimous for Tsarnaev to receive a death sentence; otherwise the penalty will be life behind bars.

During the penalty phase, Tsarnaev's lawyers will present so-called mitigating evidence they hope will save his life. That could include evidence about his family, his relationship with his brother, and his childhood in the former Soviet republic of Kyrgyzstan and later in the volatile Dagestan region of Russia.

Prosecutors will present so-called aggravating factors in support of the death penalty, including the killing of a child and the targeting of the marathon because of the potential for maximum bloodshed.

Dan Collins, a former federal prosecutor who handled the case against a suspect in the 2008 terrorist attacks in Mumbai, India, said Massachusetts' history of opposition to capital punishment will have no bearing on the jury's decision about Tsarnaev's fate.

"When you ask people their opinion of the death penalty, there are a number who say it should only be reserved for the horrific cases," he said. "Here you have what is one of the most horrific acts of terrorism on U.S. soil in American history, so if you are going to reserve the death penalty for the worst of the worse, this is it."

Liz Norden, a mother of two sons who lost parts of their legs in the bombing, said death would be the appropriate punishment: "I don't understand how anyone could have done what he did."

Information from The Associated Press was used in this report.