The jury in the Boston Marathon bombing trial is expected on Wednesday to hear more technical evidence on the investigation that followed the deadly blasts and the chaotic days afterward.
Dzhokhar Tsarnaev, 21, is charged with killing three people and injuring 264 with a pair of homemade bombs at the race's crowded finish line on April 15, 2013, and with fatally shooting a university police officer three days later.
His lawyers opened the trial early this month by saying they largely accepted prosecutors' account of the defendants' actions, but left in place his "not guilty" plea, leaving it to the federal government to prove its case.
FBI Special Agent Jessica Ulmer on Tuesday testified that agents found blood on a vehicle, a garage door and inside a private home's bathroom near the Watertown, Massachusetts, backyard where Tsarnaev was arrested, suggesting that the defendant picked his way through the sleepy neighborhood while seeking a hiding spot.
Ulmer also showed jurors two damaged iPhones recovered outside a residence near where Tsarnaev was arrested, one of which appeared to have been intentionally smashed.
Defense lawyers are seeking to portray Tsarnaev's brother, 26-year-old Tamerlan, as the driving force behind the attacks, arguing that Dzhokhar followed him out of a sense of subservience. Proving that point could persuade the jury to sentence the younger brother to life in prison without possibility of parole, rather than death.
The elder Tsarnaev died following a gunfight with police in Watertown early on April 19, 2013. Dzhokhar briefly escaped after that fight, and was found hiding in a boat after a daylong lockdown of much of the greater Boston area.
Stephen Silva, a high school friend of Tsarnaev's whom federal prosecutors contend loaned Tsarnaev the gun used in the shooting, testified under cross examination by the defense that Tsarnaev did not want him to meet Tamerlan, whom Silva said Tsarnaev described as "very strict, very opinionated."
Tsarnaev left a note in the boat that suggested the attack was an act of retribution for U.S. military campaigns in Muslim-dominated countries.
The bombing killed restaurant manager Krystle Campbell, 29, graduate student Lingzi Lu, 23, and 8-year-old Martin Richard.
