Boston Marathon bomber Dzhokhar Tsarnaev
Boston Marathon bomber Dzhokhar Tsarnaev was found guilty of all 30 charges brought against him. (Reuters)

The Boston Marathon bombing trial of Dzhokhar Tsarnaev was postponed on 30 April until 4 May, after one of the jury members fell ill.

According to WBUR, Judge George O'Toole announced that the juror has a "temporary illness," but is expected to return when the trial resumes. Five members of Tsarnaev's family were expected to testify for the defence on Thursday, but now will likely testify on Monday. The family members, who hail from Russia, are set to return home after they testify.

Testimonies on 29 April focused on Dzhokhar's childhood and his brother, the now-deceased Tamerlan Tsarnaev. Photos of the brothers were shown to the jury to demonstrate that Dzhokhar was close with his brother.

The jury also heard from paramedics who gave accounts of the different experiences they had in transporting Dzhokhar and Tamerlan to hospital after being captured. While Tamerlan was described as hostile, Dzhokhar was said to answer the paramedics questions and followed directions.

The defence is attempting to spare the 21-year-old from the death penalty, by convincing the jury that Tamerlan was in fact the mastermind of the April 2013 bombings. It has portrayed the older Tsarnaev brother as a radicalised Muslim with a deep hatred for the US.

Tsarnaev's widow's fears over bombing plot charges

The widow of Boston Marathon bomber Tamerlan Tsarnaev, Katherine Russell, fears she will be charged in the bombing plot, her attorney Amato DeLuca said on 30 April.

DeLuca's comments about Russell's fear follow revelations made by defence witness Mark Spencer that Russell made searches on her computer about the rewards of dying as a martyr's wife.

The computer expert testified that Russell conducted the searches more than a year before the bombings, before and during her husband's visit to Russia in January 2012. Searches included "rewards for wife of mujahideen" and "if your husband becomes a shahid, what are the rewards for you?" The work mujahideen is Arabic for "holy warrior" and shahid means "martyr".

DeLuca stated that Russell did not suspect her husband of anything before the 2013 attacks and that she did not notice anything amiss afterwards. DeLuca said that neither he nor his client have heard from federal officials in more than a year and she was not informed that she was being investigated.

Russell's attorney spoke to the Boston Globe on Wednesday and said, "That's what concerns us. I don't know what the government is going to do."

The 26-year-old, who took on the name Karima Tsarnaeva when she married her husband, has become the focus of more speculation as questions arise over what she knew prior to the bombings.