“Members of the jury, Omar Mateen was a monster,” Linda Moreno, one of Ms. Salman’s defense lawyers, said in her opening statement, which followed Mr. Mandolfo’s. “But Noor Salman is a mother, not a monster. Her only sin is that she married a monster.”
The opening statements set the stage for a trial that is expected to last three weeks and force Orlando to relive the trauma of the Pulse massacre. The venue for the trial, the United States District Court for the Middle District of Florida, is downtown, about two miles from the nightclub, which has been shuttered since the shooting.
A small group of Pulse victims and their families filed into Judge Paul G. Byron’s courtroom on Wednesday. Several women wiped away tears during Mr. Mandolfo’s retelling of the shooting. He spoke about Bobby Rodriguez, a clubgoer who survived the massacre by playing dead in a bathroom stall for three hours, just a few feet away from Mr. Mateen, who had holed up in the bathroom. Ms. Rodriguez later took the witness stand and described the horror of hearing people try to flee, only to be shot dead.
Ms. Salman appeared emotional during the opening statement by Ms. Moreno, her lawyer. Ms. Moreno spoke of Ms. Salman’s love for her son, who was 3 at the time of the shooting. Wearing her hair in a long ponytail and looking older and more weary than she did in the Facebook photograph published widely after her arrest, Ms. Salman dabbed her eyes with a tissue as her lawyer spoke. Later in the day, she turned around and blew a kiss at her relatives sitting in the second row.
Jury selection for the trial took more than a week, and concluded on Monday. Eighteen jurors — 12 women and six men — sat in the courtroom on Wednesday. Six of them are alternates who will not take part in deliberations unless they are needed to replace excused jurors, but none of the 18 will be told which of them are alternates until the trial concludes.
With warnings beforehand to the victims and their families in the courtroom, prosecutors played graphic videos from police body cameras, capturing Mr. Mateen’s gunfire and the screams of the wounded.
Adam Gruler, an off-duty police officer who was working as a guard at Pulse the night of the shooting, was choked with emotion on the witness stand as he recalled victims trying to flee the carnage. Nelson Rodriguez, a nightclub patron who lost two friends in the rampage, had to compose himself several times before he could finish his account of a frantic escape.
Prosecutors said Ms. Salman had participated in Mr. Mateen’s preparations for the attack, including making financial arrangements intended to provide for her and her son after his death. They cited location data from cars and cellphones showing that the couple drove to City Place, a shopping mall in West Palm Beach, and to Disney Springs in Orlando.
“The defendant and Omar Mateen were casing targets in the middle of the night with their child,” Mr. Mandolfo said.
Ms. Moreno countered that those were just family trips for Ms. Salman.
Crucial to the outcome of the trial will be what jurors make of statements that Ms. Salman gave to the F.B.I. on the day of the attack. While the shooting was still underway, law enforcement officers went to the family’s apartment in Fort Pierce, Fla., at about 4:30 a.m. and found her asleep there. She was taken to a local F.B.I. headquarters and remained with agents, speaking without an attorney, until midnight.
During that time, Ms. Salman gave statements that agents said were inconsistent. She also signed written statements appearing to acknowledge that she was aware of what Mr. Mateen had planned, and saying that she was sorry.
“The evidence was able to corroborate almost all of her admissions,” Mr. Mandolfo said.
But investigators were unable to back up Ms. Salman’s supposed admission at the time that she and Mr. Mateen had driven by Pulse and had identified the nightclub as a possible target. GPS data never placed them at Pulse.
Ms. Moreno said the agents had decided Ms. Salman was guilty before they had any evidence against her, and “were able to manipulate and coerce her.” She repeatedly called attention to the fact that agents had not recorded their conversations with Ms. Salman: “No video or audio, even though they were at the F.B.I. headquarters.”
On the night of the shooting, Mr. Mateen first went to Disney Springs, where he had been a few days earlier with his wife. He went into the local House of Blues club and bought a T-shirt, Mr. Mandolfo said, but apparently was deterred by a heavy police presence from mounting any attack there. Mr. Mateen then got back in his rented van, the prosecutor said, and used Google to search for nightclubs in downtown Orlando. The first one that came up was named Eve. The second was Pulse.
Ms. Moreno said that sequence of events contradicted the prosecution’s charges. “Omar Mateen didn’t know where he was going that night,” she said. “And if he didn’t know, how would his wife know?”
Earlier in the evening, Ms. Salman had sent Mr. Mateen a text message telling him that if his mother asked about his whereabouts, she would tell her he was out with a friend, identified only as Nemo. Prosecutors said that was a cover story Ms. Salman fabricated to avert suspicion.
The defense countered that Nemo, who lived in Maryland, told the F.B.I. that he was frequently Mr. Mateen’s own cover to cheat on his wife. According to Ms. Moreno, Mr. Mateen liked to date older women and frequented online dating sites.
Later on the night of the attack, Ms. Salman texted Mr. Mateen to ask where he was; he did not respond. She tried again after a time, reminding Mr. Mateen he had work the next day, according to the defense.
This time Mr. Mateen responded, asking if she had heard what had happened. She asked what he was talking about.
“I love you babe,” he wrote.