A trial for the widow of the gunman who killed 49 people at a gay nightclub in Orlando, Florida, in what prosecutors say was an attack in the name of Islamic State, was set to begin on Thursday with opening statements by both sides.

Noor Salman, widow of Omar Mateen, faces up to life in prison if she is convicted in US District Court in Orlando of aiding and abetting her husband and obstructing a federal investigation into the June 12, 2016 massacre at the Pulse nightclub.

Salman, 31, was at home with the couple's then-3-year-old son during the shooting rampage, which ended with Mateen's death in an exchange of gunfire with police. But prosecutors say she knew of her husband’s plans and did nothing to stop him.

The trial, which is expected to last for a month, will take place at the Orlando courthouse where protesters have been gathering during jury selection to call for a guilty verdict. Inside the courtroom, the owner of the Pulse nightclub, Barbara Poma, has been present for some of the initial proceedings.

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Although Salman initially told investigators that her husband acted without her knowledge, she later acknowledged being aware that her husband was watching Islamic State recruitment videos, had purchased an assault rifle and examined three possible attack locations, according to prosecutors.

Salman's attorneys contend the US government could not show any direct links between Mateen and Islamic State before the attack and has provided no evidence that Salman aided her husband.

In court papers filed on Tuesday defense lawyers asked that prosecutors not be allowed to tell jurors during opening statements that the shooting rampage was intended as an attack on the gay community or that Salman took part in her husband's gun and ammunition purchases.

“It was Mateen, not Noor, who decided to attack the Pulse Night Club, Mateen who chose to drive to the club, Mateen who purchased the weapon and ammunition, and Mateen who alone carried out the attack,” the defense said in court filings.

Salman was indicted on two charges: obstruction of justice for alleged false statements to federal investigators, and aiding and abetting Mateen in his attempt to provide material support to a terrorist organization. Mateen, 29, opened fire shortly after the last call for drinks on the club’s popular Latin night.

Holding hostages during his standoff with police, he claimed allegiance to a leader of the Islamic State militant group before being fatally shot.