The eldest sister of a woman killed along with her two daughters has described the moment her brother-in-law threatened to kill her if she went to the police, a jury has heard.

The bodies of 26-year old Juli Begum, and her daughters Thanha, six, and Anika, five, were found in their beds at home in Nelson Street, East Ham, in January 2007.

Her estranged husband, curry house chef Mohammed Abdul Shakur, who was 33 at the time of the offence and an illegal immigrant, went on the run and was extradited from Bangladesh in April this year.

Mr Shakur bumped into his wife's eldest sister, Gul Bahar, in the street outside her home in the village of Kalidas Para in Bangladesh in late January 2007 the same month he left the UK for that country after Juli's death.

Mother-of-six Mrs Bahar, speaking through an interpreter, described to the Old Bailey jury that her brother-in-law threatened her not to tell the police that he killed her sister and nieces.

He told her that if she said so he would kill her and her children, jurors heard.

Mrs Bahar said: "I was shaking. He said to me 'do not be scared, I will not do anything to you,' but I was very scared."

She added that all the while Mr Shakur was staying in the village she was very scared, jurors heard.

Mrs Bahar told the court she returned home from the chance encounter, telling her husband to call another sister who was in London, Sheli Begum, to tell her of the threat.

Sheli, appearing before her older sister gave evidence, had said she was not aware of money being paid to Mrs Bahar after she was shown notes appearing to reveal transfers of cash made to her by Mr Shakur.

Narita Bahra QC, defending, asked Mrs Bahar whether she was having financial difficulties at the time of her sister's death; when three of her daughters married; and whether Mrs Bahra and her teacher husband had paid for the weddings.

"My husband got a bonus. [We] spent all that money [on the weddings]. We had no problem [with money]. [The marriages were] a long time before [Juli's] death," Mrs Bahar told the court.

Asked by Miss Bahra if she was sure, Mrs Bahar said yes.

First cousins Juli and Mr Shakur had an arranged marriage in 1999 in Bangladesh with the young bride returning to the UK pregnant with Thanha. But the marriage was strained due to Mr Shakur's immigration status and the family's financial situation, the court heard last week.

Juli's sister, Sheli, raised the alarm on January 10, 2007, telling police she was concerned she hadn't heard from her sister and nieces since December 31, 2006. Sheli visited the girls' primary school who told her they'd not been in school since the holidays.

The prosecution alleged Mr Shakur murdered his wife and children most likely in the late afternoon or evening of January 1. Mr Shakur denies three counts of murder.

The trial continues.