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Despite voluminous case against Tsarnaev, questions still linger

Some of the evidence presented in the trial of Dzhokhar Tsarnaev.US District Attorney’s Office

During testimony from 95 witnesses over 16 days, new details revealed in court helped fill in the gaps in the public’s knowledge of the Boston Marathon bombings and the aftermath.

But even after all the testimony and evidence was presented, some questions about the bombing — and the Tsarnaev brothers — remain.

Where were the bombs that went off at the Marathon made?

Several prosecution witnesses testified that tools believed to have been used to make the bombs were found in Tamerlan Tsarnaev’s Cambridge apartment, and those tools tested positive for explosive powder. But that same witness said that a large mess would have been left behind, and there was no trace of a mess in the Cambridge apartment or in Dzhokhar Tsarnaev’s UMass Dartmouth dorm room. One FBI agent testified that investigators never identified the bomb-making site.


Did the brothers ever test their homemade bombs?

In March 2013, Tsarnaev allegedly told two of his friends from University of Massachusetts Dartmouth, Azamat Tazhayakov and Dias Kadyrbayev, that he knew how to make a bomb, court records in the friends’ cases show, but no evidence was presented at the trial about whether any practice bombs were detonated.

How did the brothers obtain the explosive powder used in the bombs?

According to FBI agent Edward S. Knapp, the two bombs that exploded near the Marathon finish line were made with six-quart pressure cookers that each probably contained between 8 and 16 pounds of explosive powder. The bomb that Tsarnaev allegedly threw at police in Watertown was made with a 4-quart pressure cooker and held about half that amount; and a plastic container found at the scene of the Watertown shootout contained 3 pounds of explosive powder.

Authorities have suggested that the powder was taken from fireworks, and the Globe has interviewed a New Hampshire assistant manager at Phantom Fireworks in Seabrook, N.H., who said she sold fireworks in February 2013 to Tamerlan Tsarnaev. But there was no testimony about that during the trial. Also, FBI chemist David McCollam testified that it would take about 15 mortar-style fireworks to obtain 1 pound of explosive powder, so the brothers would have had to empty several dozen mortars just to fill the smaller pressure cooker.


Will Tsarnaev’s parents, siblings, or other family members testify or appear in court?

That remains unclear, however Tsarnaev’s two older sisters attended his arraignment in July 2013. His mother and father now live in Dagestan. Zubeidat, Tsarnaev’s mother, proclaimed her son’s innocence after his arrest. She could possibly be arrested if she returned for the trial, however, as she has a warrant for her arrest issued in June 2012 for failing to resolve charges of shoplifting about $2,000 in dresses from a Lord & Taylor department store in Natick.

What happened to Tamerlan’s wife, Katherine Russell? Why hasn’t she been charged or called to testify?

Russell was the subject of a federal grand jury inquiry, and her parents testified before that grand jury. However, Russell was never charged and has barely been mentioned during the bombing trial. No evidence has been presented that she knew about the bombing, though authorities said many of the suspected bomb making materials were found in the 800-square-foot Cambridge apartment she shared with Tamerlan Tsarnaev and their toddler daughter. Her lawyer has insisted she knew nothing about the attacks. A local television report indicated that Russell was living with Tsarnaev’s sisters in New Jersey, though her current whereabouts are unknown. Her lawyer has not returned calls.


Where were the Tsarnaev brothers heading if they hadn’t been stopped in Watertown?

Dun Meng, the Tsarnaev brothers’ carjacking victim, said that the brothers talked about going to New York City, though their scramble for cash on the night of April 18, 2013, suggests they may have been making things up as they went along. Evidence found in the Tsarnaev’s car after the shootout included some of Tamerlan Tsarnaev’s official documents, including a short-term (expired) residency permit for Dagestan, written in Russian, and his Cambridge Rindge and Latin High School diploma, which could suggest that he was trying to obtain documents to leave the country.

Tamerlan Tsarnaev was passport-less: He had an expired Kyrgyzstan passport and no US passport.

Dzhokhar Tsarnaev had a US passport, and spoke to friends about wanting to go to Dagestan, though there’s no evidence that he had his passport with him the night of April 18, 2013.

Tamerlan Tsarnaev had also wired $900 by MoneyGram to his mother in Dagestan the day before the Marathon bombing.

How was MBTA officer Richard Donohue injured?

Tsarnaev was not charged directly with shooting Donohue, who was shot in Watertown, but he was charged with carjacking resulting in injury — a charge that includes Donohue’s injury.

This charge could be a contentious one for jurors. No evidence was introduced during the trial that showed that Dzhokhar Tsarnaev or his brother fired the bullet that struck Donohue. Instead, Tsarnaev’s lawyers sought multiple times to show that Donohue was hit by friendly fire, specifically by officers who were stationed at the northeast corner of the intersection of Dexter and Laurel streets who fired at Tsarnaev as he drove west on Laurel Street.


Donohue was stationed at the southeast corner. He never fired his gun.

How could Tsarnaev elude the police for more than 15 hours?

Only one officer testified that he chased Tsarnaev as he fled the shootout, and he said he did so only after making sure other officers were OK.

The stolen Mercedes SUV that Tsarnaev drove to escape was found roughly a half mile away at the intersection of Lincoln and Spruce Street, and Tsarnaev was found hiding in a boat parked in a driveway a few blocks away on Franklin Street.

An FBI agent testified that investigators found blood on a parked vehicle, a garage door, and inside a private home’s bathroom, suggesting Tsarnaev wandered through the neighborhood in the dark before finding his hiding place. Investigators also found carjacking victim Dun Meng’s debit card and two damaged cellphones behind a shed at 63 Franklin St. A law enforcement official testified that authorities did not use police dogs to try to track Tsarnaev because they feared the dogs might set off hidden explosives.

What about the unsolved 2011 Waltham triple murders and Tamerlan’s potential role?

It’s possible more information about that case could emerge in the penalty phase.


Milton J. Valencia can be reached at mvalencia@globe.com. Follow him on Twitter @miltonvalencia.