FORMER biology student Dzhokhar Tsarnaev is facing the death penalty after jurors found him guilty of bombing the Boston Marathon.

Tsarnaev, 21, has been convicted of orchestrating the April 2013 terror attack, which killed three and left 264 injured when twin bombs detonated at the crowded finish line.

He plotted and carried out the bombings with his older brother, Tamerlan Tsarnaev, who was killed following a gun battle with police as they attempted to arrest him.

The defence argued that Tsarnaev was pressured by his radicalised brother, who was the true mastermind behind the attacks.

However, the jury was unconvinced and after two days of deliberations found the one-time marine biology student and aspiring dentist guilty on all 30 charges.

Tsarnaev kept his hands folded in front of him and looked down at the defence table in the Boston courtroom as the guilty verdicts were read on Wednesday.

The jury will now decide whether he should be sentenced to death or receive life in prison.

Survivors of the attacks and family members of those killed - including the parents of eight-year-old Martin Richard, the youngest victim - were in court to hear the decision.

The blasts also killed restaurant manager Krystle Campbell, 29, Chinese exchange student Lingzi Lu, 23.

In addition, Tsarnaev was found guilty of murdering 27-year-old college police officer Sean Collier.

Mr Collier was found in his car on the Massachusetts Institute of Technology campus with multiple gunshot wounds hours after the FBI released surveillance photographs of the brothers.

It came just one week shy of the bombings' second anniversary on April 15.

A second phase of the trial will now begin, during which additional testimony will be heard before the jury determines its sentence.

Tsarnaev, an ethnic Chechen, was born in Kyrgyzstan but moved to the United States with his family aged eight, under political asylum.

They settled in Cambridge, Massachusetts and Tsarnaev and his older brother became naturalised US citizens in 2012.

Prosecutors laid out evidence showing that Tsarnaev, who was brought up as a Muslim, had read and listened to jihadist materials. They also produced a note he had penned while in hiding after the attacks which described them as retribution for US military campaigns in Muslim-dominated countries.

Boston Mayor Martin Walsh said he hoped the verdicts offered "a small amount of closure".

He added: "The incidents of those days have forever left a mark on our city."