New bombing details emerge as Boston pauses in remembrance

BOSTON – The nation stopped to remember the tragic events that began a week ago with twin explosions at the finish line of the Boston Marathon as prosecutors charged a suspect in his hospital room with using a weapon of mass destruction in the attack.

At precisely 2:50 p.m., bells tolled throughout Boston to mark the moment that the first explosion tore through the city’s heart, killing three and injuring more than 200 -- an updated figure on the wounded.

President Obama, who visited Boston last week to participate in an interfaith service, commemorated the tragedy by pausing in Washington. Trading was halted on the New York Stock Exchange.

FULL COVERAGE: Boston Marathon attack

Gov. Deval Patrick joined members of the Massachusetts Legislature and other state employees in observing a moment of silence on the steps of the 215-year old State House on Beacon Hill, looking out on downtown Boston. Under a mostly sunny sky on a brisk early-spring afternoon, several hundred bowed their heads at the foot of the Capitol’s golden dome.

“God bless the people of Massachusetts. Boston Strong,” the governor said afterward, as the sound of bells was heard in the distance.

A large crowd had gathered at the makeshift memorial that has sprung up near the marathon finish line. American flags fluttered in the breeze, and some people appeared to be praying.

As the country paused, new details emerged about the week of terror that ended last Friday with the capture of suspect Dzhokhar Tsarnaev, 19. His brother, Tamerlan, 26, was killed during a massive manhunt.

Dzhokhar Tsarnaev remains in serious but stable condition at Beth Israel Deaconess Medical Center, unable to speak because of a gunshot wound to the throat.

He has, however, begun to provide some written responses to questions from authorities seeking information about any other potential plots or explosive devices, a federal law enforcement official said Monday.

U.S. Magistrate Marianne B. Bowler went to Tsarnaev’s heavily guarded room at the hospital and advised him of his legal rights and read the criminal charges against him, according to notes in the court case file.

He is accused of one count of using and conspiring to use a weapon of mass destruction and one count of malicious destruction of property by means of an explosive device resulting in death.

Federal prosecutors warned Tsarnaev that he could face the death penalty if convicted. They asked the magistrate that he be kept in custody.

At that point, Tsarnaev agreed to an order of voluntary detention and declined to answer questions on whether he was suitable for release on bail, according to the notes from the court clerk.

Bowler scheduled a court hearing for May 30 to determine if there is probable cause that Tsarnaev was involved in the bombings.

Bowler added, according to the notes, that she was “satisfied that the defendant is alert and able to respond to the charges.”

Tsarnaev was not asked how he intended to plead.

Tsarnaev has been hospitalized since his capture Friday night with apparent gunshot wounds to the head, neck, legs and hand, according to a separate criminal complaint filed Monday.

The session ended when Bowling remanded Tsarnaev to the custody of the FBI and the U.S. Marshals Service.

Tsarnaev was represented by the federal public defender’s office in Boston.

The affidavit filed with the complaint describes a compelling timeline of events since the attack last week as prosecutors begin to officially lay out their case.

The court documents give the following reconstruction of events, according to investigators:

The first explosion takes place approximately 2:49 p.m. Monday in front of 671 Boylston St., and the second occurs about a block away at 755 Boylston St. Explosive devices were placed near the metal barriers that lined the street at the finish line area of the marathon, the highlight of Boston’s Patriots’ Day celebration.

According to video from a security camera, approximately 11 minutes before the first blast, two young men are seen turning left onto Boylston from Gloucester Street. Both are carrying large backpacks. One man is wearing a dark baseball cap and has been identified as Tamerlan Tsarnaev. The other, in a backward white cap, called Bomber Two, is identified as the surviving suspect, Dzhokhar Tsarnaev.

The brothers, of Chechen heritage, are seen on the video walking east along the north side of Boylston Street to the finish line of the marathon. The elder brother is in front. At 2:41 p.m., the pair are caught by a security camera above the doorway of the Forum Restaurant at 755 Boylston. They are standing together about half a block from the restaurant.

By 2:42, approximately seven minutes before the first explosion, the older brother separates himself from the crowd and walks to the finish line, still wearing a backpack.

About 2:45 p.m., the younger brother also walks east on Boylston to the finish line.

According to the affidavit, he appears to have his right hand “hooked under the strap of his knapsack and a cellphone in his left hand.” Some 15 seconds later, he is seen stopping in front of a restaurant near the metal barrier to the street with his back to the camera, facing the runners. “He then can be seen apparently slipping his knapsack onto the ground,” the affidavit says.

About 30 seconds before the first explosion, the second suspect lifts the cellphone to his ear and keeps it there for 18 seconds. After he finishes the call, the crowd reacts to the explosion with almost every head turning to the finish line in alarm.

The suspect, however, appears calm, according to the document. He glances to the east and then calmly moves west away from the finish line. He is moving without his backpack, which is still on the ground. About 10 seconds later, there is a second explosion in the area, the affidavit says.

Both suspects are identified by license photographs at the Massachusetts Registry of Motor Vehicles, federal officials say.

It is not until about 5 p.m. Thursday that officials reveal they have suspects in the case. They release photos and video of the suspects and ask the public for help.

Near midnight, according to the affidavit, an individual carjacks a vehicle at gunpoint in Cambridge. The owner later tells officials that a man approached him while he was sitting in his car and tapped on the window. The driver rolls down the window and the assailant reaches in, opens the door and points a weapon.

“Did you hear about the Boston explosion?” the assailant says. “I did that.” The attacker then removes the magazine from his gun and shows the car owner that it has a bullet. He reinserts the magazine and says, “I am serious.”

The assailant forces the man to drive to a location where a second man enters the car. The pair put something in the trunk. The original assailant moves to the driver’s seat and the other assailant is in the rear seat. The owner of the vehicle is in the front passenger seat.

They drive off and the assailants demand money and eventually an ATM card and password. They drive to an ATM machine, where the assailants attempt to withdraw cash. They then drive to a gas station in the vicinity of 816 Memorial Drive in Cambridge, where the assailants get out of the car and the owner escapes. The assailants get back in the vehicle and head to Watertown.

(There is no mention in the federal documents of the pair shooting an MIT officer, but those details are expected to be released when state officials bring charges. Authorities have already linked the suspects to the death of the officer.)

As the pair drive down Dexter Street, they throw at least two small improvised explosive devices out of the car, according to officials. A gunfight ensues, in which officials have previously said that more than 200 shots were fired.

One of the men escapes in the car, which is later found abandoned a short distance away with an unexploded device inside. Two unexploded devices are found at the scene of the shootout “as well as remnants of numerous unexploded” devices.

According to fingerprints and a driver’s license, the suspect killed in the shootout has been identified as Tamerlan Tsarnaev. The state photographs were also used to identify Dzhokhar Tsarnaev, a naturalized citizen who entered the United States on April 12, 2002. His dead brother is identified as a permanent resident but not a citizen.

Officials also said that the explosive devices used at the marathon scene were pressure-cooker-style bombs containing metal shards. A similar device was found in the stolen car, they said.

By Friday evening, police find an individual in a boat outside a house at 67 Franklin St. in Watertown. Authorities approach and there is gunfire. The wounded individual, with identification cards naming him as Dzhokhar Tsarnaev, is captured. He has apparent gunshot wounds to his head, neck, legs and hand, according to the affidavit.

After receiving aid at the scene, he is hospitalized.

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michael.muskal@latimes.com

michael.memoli@latimes.com