The trial of Tahawwur Rana is being closely watched worldwide for what testimony might reveal about suspected links between the Pakistani militant group blamed in the attacks and the nation’s main intelligence agency, which has been under increased scrutiny since Osama Bin Laden was killed by US forces on May 2 outside Islamabad.

During opening statements, Assistant US Attorney Sarah Streicker confirmed that David Coleman Headley would testify at Rana’s trial. Headley is cooperating with the government after pleading guilty to taking photos and videos of targets in Mumbai before the rampage that killed 160 people including six Americans over three days in India’s largest city.

Though Streicker did not give any indication that the trial would give any clues about the global fight against terrorism, Headley’s testimony is of particular interest because he may discuss allegations that Pakistan’s government knew — or possibly helped plan — the Mumbai attack blamed on the militant group Lashkar-e-Taiba.

Rana, 50, has pleaded not guilty and his attorneys say their client was simply duped by his longtime friend and didn’t know what was in store. Headley and Rana, a Pakistani-born Canadian who has lived in Chicago for years, met at one of Pakistan’s most prestigious military boarding schools and stayed in touch as adults.

Defense attorney Charles Swift told jurors that Headley was a “manipulative man” who “balanced multiple lives” including working for Laskhar-e-Taiba, Pakistani intelligence and the US Drug Enforcement Administration at the same time.

But Steicker said Rana knew what he was getting into. She said Rana provided cover for Headley and led him to pose as a representative for his Chicago-based immigration business. She also said Rana knew and supported a separate plot that never happened against a Danish newspaper that had printed cartoons of the Prophet Muhammad and that Rana and Headley had talked about at least four other plots. She gave no further details.

“The defendant knew all too well that when Headley travels to a foreign country, people may die,” Streicker said.

Streicker said the government will show jurors evidence including e-mails between Headley and Rana that were written in code. She said Headley considered Rana “his best friend in the world.” “The defendant didn’t carry a gun or throw a grenade. In a complicated and sophisticated plot, not every player carries a weapon. People like the defendant who provide support are just as critical to the success,” Streicker said.

Attention to Rana’s trial has increased in recent weeks, especially amid questions about whether Pakistan’s Inter-Services Intelligence agency, known as the ISI, had knowledge of Bin Laden’s whereabouts. Security has been tightened, with more armed guards and a metal detector outside the courtroom in downtown Chicago, and many reporters from Denmark and India are covering the proceedings.

“The trial has the potential to be an irritant and already has been in what’s happening in the US-Pakistani relationship,” said Daniel Markey, a fellow at the Council on Foreign Relations. “Given the Indian media attention, it’ll stoke Indian concern about what Pakistan has been up to.” Rana is the seventh name on the indictment, and the only defendant in custody. Among the six others charged in absentia is “Major Iqbal” and Sajid Mir, allegedly another Lashkar-e-Taiba supervisor who also “handled” Headley.

Some experts are doubtful the trial will reveal much new.

For one, federal prosecutors may work hard to keep any sensitive information from surfacing in the courtroom, and Headley’s credibility has been under question.

Headley, born Daood Gilani, reached a plea deal with prosecutors in the terrorism case in exchange for avoiding the death penalty and avoiding extradition. He’s also been an informant for the DEA after a drug conviction.

Former Assistant US Attorney John Kocoras, who has worked on terrorism cases, said he was skeptical the trial would offer much more.

“I don’t anticipate that the prosecutors will delve into deeper geopolitical issues,” he said. “The prosecution generally approaches that in a formulaic way without overly appealing to emotion.” During last week’s jury selection, Rana’s attorneys had said they wanted a jury that wouldn’t be biased against their client, who is Muslim. Questions of potential jurors in open court focused on their views on Islam, terrorism, and US citizenship.

About half a dozen were dismissed after admitting to having biases against Muslims or saying they were afraid to be involved in a terrorism case. According to the judge, one juror had written on his questionnaire, “Terrorists are mainly Muslims, or am I wrong?” The jury of 12 people is mostly minorities and women. Six alternates were also chosen for the trial that US

District Judge Harry D. Leinenweber said would last about a month.