A Rwandan woman who won political asylum in the US after hiding her family's role in the 1994 genocide has been convicted in a New Hampshire court of lying about her own part in the mass killings.

Beatrice Munyenyezi, 43, was immediately stripped of the US citizenship she had gained a decade earlier in the same courthouse where she was found guilty on Thursday of making false statements to officials in order to cover up how she selected Tutsis to be raped and murdered. She faces up to 10 years in prison and then likely deportation to face a trial in Rwanda for genocide.

Munyenyezi settled in Manchester, New Hampshire, with three young daughters in 1998 after claiming to have been persecuted in Rwanda.

She caught the attention of the US authorities several years later after giving false testimony on behalf of her husband and mother-in-law who were later sentenced to life in prison for genocide and other crimes against humanity by an international tribunal.

Prosecutors alleged that Munyenyezi had a "front row seat" during the mass killings of about 800,000 Tutsis because her mother-in-law, Pauline Nyiramasuhuko, served as the minister of family and women's affairs in the Hutu government which organised the slaughter.

When the killings began in April 1994, the government sent Nyiramasuhuko to her home city, Butare, to order the governor to begin murdering Tutsis there. When the governor refused he was killed and Nyiramasuhuko took charge along with her son and Munyenyezi's husband, Arsene Shalom Ntahobali, a leader of the interahamwe militia at the forefront of the murders.

The killings in Butare were among the most intense of the genocide.

Nyiramasuhuko had the presidential guard brought into the city to kick start the slaughter.

Prosecutors said they began investigating Munyenyezi after she gave evidence at the International Criminal Tribunal for Rwanda (ICTR) in 2006 in which she testified that there was no roadblock with her husband and other militiamen butchering people outside the Butare hotel, owned by her in-laws, in which she was staying.

Munyenyezi told the ICTR that she had seen no killing at all. "No, I never saw dead bodies," she said.

But numerous witnesses at the ICTR trial recounted murders, rapes and other crimes at the roadblock. In addition, a US Defense Department satellite photographed the site.

Prosecutors mocked Munyenyezi's claim not to have seen any killings outside her door.

"She had a front row seat to the genocide, to the most vicious roadblock in town," the prosecutor, John Capin, told the jury.

Witnesses described Munyenyezi conducting selections of who would die according to whether identity cards said a person was Tutsi or Hutu.

"If I'm checking IDs at roadblocks, knowing that person is going to be clubbed to death, I'm as responsible as if I wielded the machete myself," said Capin.

Prosecution witnesses included Consolee Mukeshimana who described Munyenyezi as checking identity cards at the roadblock for two hours on one occasion, and directing Tutsis to their deaths.

Mukeshimana said that at the beginning of the genocide she survived a massacre at the health centre where she worked by hiding among the corpses. She then fled to the house of her sister whose husband, a Hutu, was Munyenyezi's nephew. The husband took Mukeshimana to the roadblock outside the family hotel thinking Munyenyezi would help. Instead she was hostile.

Mukeshimana said she saw Munyenyezi separating Tutsis. "They would lead them towards, behind the hotel, going to kill them," she said. "But girls and women would first be brought to a house that was next to the hotel, in the basement, and from there you could hear them screaming."

The prosecution said the women and girls were raped in the basement before being murdered.

Mukeshimana said she escaped death when her brother in law told the militia that he would kill her but then hid her.

Another witness, Thierry Sebaganwa, wept in court as he described how Munyenyezi had taunted him by telling the then 21 year-old that the Hutu militia had just cut off his mother's head.

The defence painted the accusers as liars who claimed to see incidents they did not witness, and said they were under pressure from the Rwandan government to falsely implicate Munyenyezi.

"You don't have to take these witnesses at their word," the defence lawyer, David Ruoff, told the jury. "And given where they're coming from, and what they'll go back to, you should not."

Ruoff described Munyenyezi as a loyal wife who followed her husband to Butare out of duty and who spent the genocide at the hotel caring for their baby daughter and was newly pregnant with twins. Prosecutors said that Munyenyezi was only two months pregnant.

Munyenyezi, who was nearing completion of a degree in politics and society at the University of New Hampshire when she was arrested in 2010 and held in prison, was convicted in a second trial after the jury in a first one a year ago failed to reach a verdict.

On that occasion, witnesses described how Munyenyezi paid rapists with food and beer, selected Tutsis for death and shot a nun before a cheering mob. Survivors also accused her of taking Tutsis, including women carrying children, to a pit where they were butchered.

Jurors in the first trial said they were uncertain about some of the evidence of Munyenyezi's direct participation in atrocities, in part because they were confused by shambolic translations, but were persuaded she had lied about her associations with the organisers of the genocide.

Prosecutors tailored their case in the second trial to shift the emphasis to Munyenyezi's leadership in deciding who would die and her membership of the ruling party responsible for leading the genocide.

Last year, Munyenyezi's sister, Prudence Kantengwa, was convicted of perjury and obstruction of justice in a separate trial and sentenced to 21 months in prison for failing to declare she was also in Butare in 1994 and had political connections to the perpetrators of the genocide.

Munyenyezi's mother in law, Nyiramasuhuko, was the first woman convicted by the ICTR where she received a life sentence after being convicted of seven charges including genocide, crimes against humanity and incitement to rape. Her trial heard how she told militiamen "before you kill the women, you need to rape them". On one occasion she ordered petrol poured over a group of women who were then burned to death after being raped.

Munyenyezi's husband, Ntahobali, also received a life sentence.