(CNN) The Orlando shooter and his wife exchanged text messages during the Pulse nightclub rampage, a law enforcement official briefed on the investigation told CNN. 
 
 Around 4 a.m. on June 12, about two hours after he started the attack and while holed up in a bathroom, Omar Mateen texted his wife, Noor Salman, asking if she'd seen the news, the official said. 
 
 At one point, she responded with a text saying that she loved him. Salman also tried calling her husband several times during the standoff, a second law enforcement official said. 
 
 The timing of her calls came after reports of the attack had emerged, and apparently after she realized her husband might be responsible. He didn't answer, the official said. 
 
 It's not clear if Salman made any attempt to report her husband during that time. 
 
 Salman is coming under increasing scrutiny as police investigate the killing of 49 people and wounding of at least 50 at the gay nightclub in Orlando. Authorities say Mateen carried out the killing with a Sig Sauer MCX semi-automatic assault-style rifle and a pistol. 
 
 Salman apparently gave conflicting accounts about what she knew of Mateen's intentions in the hours before the attack. authorities said. She also told investigators that in the weeks before the attack, Mateen spent thousands of dollars, including for the guns used in the attack. 
 
 Mateen and Salman married in 2011. They have a 3-year-old son and lived in Fort Pierce, about two hours from the massacre. 
 
 A U.S. attorney plans to bring evidence before a federal grand jury to determine whether charges will be filed, two law enforcement officials said. 
 
 Facebook postings 
 
 Mateen also vented on Facebook before and during the massacre. 
 
 "America and Russia stop bombing the Islamic state," the gunman wrote, according to the chairman of the Senate Committee on Homeland Security and Governmental Affairs. 
 
 "You kill innocent women and children by doing us airstrikes ... now taste the Islamic state vengeance." 
 
 Then, in his final post, an ominous warning: ''In the next few days you will see attacks from the Islamic state in the usa." 
 
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 The messages were described in a letter from committee Chairman Ron Johnson to Mark Zuckerberg, asking the Facebook CEO to provide "all Facebook data on Mr. Mateen's activities on his account and any affiliated Facebook accounts." 
 
 It's not the only time Mateen invoked ISIS during his rampage early Sunday. In the middle of killing 49 people, Mateen also called 911 to pledge allegiance to the terror group and CNN affiliate News 13 to say, "I did it for ISIS. I did it for the Islamic State." 
 
 And an analysis of Mateen's electronic devices showed searches for jihadist propaganda, including videos of ISIS beheadings, an official said. 
 
 Reported gun store visit 
 
 The owner of a Florida gun store said Thursday that employees contacted the FBI four or five weeks ago because they became suspicious when Mateen tried to purchase body armor and a large amount of ammunition. 
 
 Robert Abell of Lotus Gunworks in Jensen Beach said a man asked for soft and then hardened body armor but was told the store didn't carry that merchandise. 
 
 During his visit, the man spoke on the phone to somebody in a foreign language and asked to buy 1,000 rounds of ammunition -- a request the store turned down, Abell said. 
 
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 The store called the FBI with the suspicions, Abell said, but didn't know the man's name. 
 
 The FBI investigated another incident reported by the gun store owner that coincided with Mateen's possible visit, three law enforcement officials told CNN. 
 
 Agents originally looked into a call from the store about a group of suspicious foreign men appearing to be of Middle Eastern descent, who were buying police gear. 
 
 The FBI tracked down the men, who were visiting government security officers from a Middle Eastern country. The purchase was not deemed suspicious, the sources said. 
 
 When the FBI closed the matter with the store, an employee mentioned another unidentified suspicious man who days before had tried to buy Level 3 body armor. 
 
 There was no name or any purchase record to review. The FBI asked the person at the store if there was surveillance footage or a car description or license plate. There wasn't. 
 
 After the shooting, store employees realized the man was Mateen, Abell said. 
 
 The FBI had no official comment on the matter when reached Thursday night. 
 
 Spokesmen for the Florida Department of Law Enforcement and the Martin County Sheriff's Office said the agencies don't have any records of receiving calls from Lotus Gunworks. 
 
 ISIS, or personal conflict? 
 
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 Despite mounting pledges of allegiance to ISIS, some say they believe Mateen was actually fueled by struggles with his sexuality -- and may have latched on to ISIS as a vehicle for his anger. 
 
 Several regulars at the gay nightclub said the gunman visited frequently over the past few years. Cord Cedeno said Mateen saw him at Pulse and messaged him on Grindr, a gay dating app. 
 
 Cedeno said he wasn't interested in Mateen, but his friend was. 
 
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 "One of my friends ... has been speaking with him since 2007, on and off," on another gay dating app, Cedeno said. 
 
 "(Mateen) sent him a picture of his private part, and my friend actually was attracted to him. He almost went and hooked up with him." 
 
 FBI agents are interviewing people who claim they met the gunman on gay dating apps, a law enforcement official said. Those claims "certainly change the perspective," the source said. 
 
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 CNN military analyst Lt. Gen. Mark Hertling said the gunman's complex background makes the investigation challenging. 
 
 "I'm not a psychiatrist, but the struggle with his humanity, his sexuality, combined with the potential for putting the onus on an organization that's asking people to do this -- asking extremists to do these kinds of things -- is an interesting dynamic," he said. 
 
 "And that's the thing that makes this case so extremely difficult." 
 
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 The gunman's ex-wife, Sitora Yusufiy, said she was not sure about his sexuality. 
 
 "It doesn't surprise me that he might be gay," she said. "And it doesn't surprise me that he was leading two totally different lives and was in such deep conflict within himself." 
 
 But the gunman's father, Seddique Mateen, has said he didn't think his son was gay. He emphasized that Mateen had a wife and child. 
 
 Victim's video 
 
 Throughout Orlando, survivors mourned the dead and recalled their experience. 
 
 Miguel Leiva shot cell phone video while huddled inside a bathroom with about 16 other people, he told CNN's Anderson Cooper on Thursday night. 
 
 The video showed people passing a cup of water around. One man was choking on his own blood, Leiva said. They whispered because they feared the gunman, who twice came back and fired his weapon, would return. 
 
 "I just remember you can smell the blood, there was so much blood," Leiva said. "All my clothes was full of blood. We were sitting down and there was a huge puddle of blood." 
 
 Only five or six people made it out alive, he said. Leiva was shot in the foot and leg. 
 
 "So many innocent people just there to have a good time." ||||| Starting in 1996, Alexa Internet has been donating their crawl data to the Internet Archive. Flowing in every day, these data are added to the Wayback Machine after an embargo period. ||||| The owner of a Florida gun store said he tried to alert the FBI to a "very suspicious" man later identified as Orlando nightclub shooter Omar Mateen after Mateen tried to buy body armor and bulk ammunition from the store. 
 
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 Robert Abell, a co-owner of Lotus Gunworks in Jensen Beach, Florida, told ABC News today that a man entered the store five or six weeks ago and asked specific questions about high-end body armor. When employees said the store didn't carry the body armor he wanted, Abell said, the man made a phone call in a foreign language, hung up and then asked about ammunition in bulk. 
 
 Abell said a member of his staff thought the questions were "odd" and made him uncomfortable, so he turned the man away. 
 
 Abell added that they thought the man was "very suspicious," so they called the local FBI office in West Palm Beach and reported the incident. But they didn't have the man's name, since no sale was made, and the only surveillance footage they had was grainy. 
 
 "We gave them information and everything that took place, and that was the end of the conversation," he said. 
 
 There was a follow-up conversation with agents, Abell said, but the FBI never visited the store or investigated further. 
 
 That was the end of it until he saw the news about the Orlando shooting that took place early Sunday morning and images of the man identified as the killer: Mateen, the man who Abell said was in the store. 
 
 "He slipped through the cracks," Abell said. 
 
 He said his staffers contacted the FBI after the shooting to remind them about their run-in with the suspicious man. The store's surveillance tape, however, had long since been overwritten, he said. 
 
 Public affairs officials for the FBI's Miami field office, which oversees the West Palm Beach satellite office, and at headquarters in Washington, D.C., declined comment. 
 
 Earlier this week the FBI faced sharp questions for having investigated Mateen twice in 2013 and 2014 for purported ties to extremists and determining that he was not a threat. After reviewing those investigations, FBI Director James Comey said Monday he hadn't seen anything that his "agents should have done differently." 
 
 Comey also stressed the law enforcement motto "See something, say something." 
 
 "Every single one of our cases, as we look back, someone always sees something they should have told us, and they didn't," he said. "So our request to you is please don't let them make you work into a state of anxiety that is disabling. Find ways to channel that into a healthy awareness of your surroundings and live your lives." 
 
 Abell said he thought his team had "done [its] job" after contacting authorities. 
 
 Mateen, 29, began his attack on a popular gay Orlando nightclub at around 2 a.m. Sunday. At some point that morning, he posted on Facebook his allegiance to ISIS, a demand that the U.S. and Russia to "stop bombing" the Syrian-based terrorist group and a warning of attacks to come, FBI officials said. 
 
 "You kill innocent women and children by doing us airstrikes..now taste the Islamic state vengeance," Mateen posted, according to officials in the FBI’s counterterrorism division. "In the next few days you will see attacks from the Islamic State in the usa." 
 
 He killed 49 people before being gunned down by police. ||||| A somber President Barack Obama met privately Thursday with wounded victims and families of the 49 people slain in the Pulse nightclub massacre, telling them, “our hearts are broken, too.” 
 
 “Today, once again, as has been true so many times before, I held and hugged grieving family members and parents,” Obama told reporters after the two-hour meeting at the Amway Center in downtown Orlando. “And they asked, ‘Why does this keep happening?’” 
 
 After leaving the arena, the presidential motorcade drove to the nearby Dr. Phillips Center for the Performing Arts, where a makeshift memorial to the victims has sprung up on the lawn. 
 
 There, Obama and Vice President Joe Biden laid bouquets of 49 white roses. The two stood in silence for several moments, looking down at the hundreds of flowers, signs and tributes placed inside a rainbow paper chain. 
 
 PICTURE GALLERY: Orlando residents continue to recover in the aftermath of a mass shooting at Pulse nightclub that left 49 victims dead and another 53 injured. President Barack Obama and Vice President Biden visited Orlando on Thursday to pay respects to the victims of the Pulse nightclub shootings. 
 
 “Four days ago, this community was shaken by an evil, hateful act,” Obama said. “Today we are reminded of what is good — that there is compassion, empathy, decency, and most of all, there is love. That is the Orlando we’ve seen in recent days and that is the America we have seen.'' 
 
 The families, Obama said, had “grief beyond description.” 
 
 “Through their pain and through tears, they told us about the joy their loved ones had brought to their lives,” Obama said. “They talked about their sons and their daughters. So many young people in their 20s and 30s … One young woman who was just 18 years old.’’ 
 
 Obama also spoke about the mother who gave her life for her son, as well as the former Marine “whose quick thinking saved hundreds of lives.” 
 
 “These families could be our families,” Obama said. “In fact, they are our families. They’re part of the American family. On behalf of the American people, our hearts are broken, too. We stand with you. We’re here for you. And we are remembering those you loved so deeply.” 
 
 He said the U.S. must continue to be “relentless” against ISIS and Al Qaeda terror networks. 
 
 “We are going to destroy them,” he said. 
 
 But he pointed out that the last two terrorist attacks on the U.S. — Orlando and San Bernardino — were “home grown.” 
 
 "Those families could be our families. In fact, they are our families. They're part of the American family." — President Obama 
 
 The attack was done by “a single killer with a powerful assault rifle,” Obama said. 
 
 “If we don’t act,” Obama said, “we will keep seeing more massacres like this, because we'll be choosing to allow this to happen. We’ll have said we don’t care enough to do something about it.” 
 
 Obama also called the shootings an attack on the LGBT community, calling Pulse a “sanctuary ... violated in the worst way imaginable.” 
 
 Spectators were not allowed to attend the president’s remarks at the Dr. Phillips Center, but crowds collected in parking lots across South Street, hoping to catch a glimpse of the president or snap a picture. 
 
 “It’s good for everybody,” said Maria Herrera, who joined a throng outside the church. “We feel secure because our president is here. We are very happy, because he is going to help the people who lost their relatives.” 
 
 Herrera, who moved to Central Florida from Peru, held a pair of balloons and two signs: “Peruvians against terrorism,” said one, while the other proclaimed that “the church loves LGBT.” 
 
 The president’s four-hour trip began when Air Force One arrived at Orlando International Airport at 12:45 p.m. Biden came separately on Air Force Two, also arriving at OIA. 
 
 The president was greeted on the tarmac by Gov. Rick Scott, U.S. Sen. Marco Rubio, Orlando Mayor Buddy Dyer and Orange County Mayor Teresa Jacobs. 
 
 The motorcade, escorted by dozens of police motorcycles, arrived at Amway at about 1:30 p.m., with the vehicles entering the building through huge bay doors. 
 
 Christina Dangelo of Sanford watched as the president arrived there. 
 
 “I came here to show support for the victims and their families and to show support for our country, and what's going on in Orlando,” she said, calling the president's visit “very thoughtful of him.” 
 
 Dangelo said Target, where she works, held a moment of silence for the victims, two of whom she said also worked for the retailer. 
 
 “It's been very hard on everybody, but I feel the love and the support, and everybody coming together ... to support each other,” she said. 
 
 POTUS motorcade arrives at Amway Arena to provide support for families/survivors of Pulse nightclub shooting POTUS motorcade arrives at Amway Arena to provide support for families/survivors of Pulse nightclub shooting SEE MORE VIDEOS 
 
 Outside the arena, Democratic U.S. Sen. Bill Nelson, who flew from Washington with Biden, said Obama and Biden also met in the arena with the Orlando officers involved in the standoff at Pulse. 
 
 Nelson said he agrees with the president that the violence in Orlando must spur action on gun legislation. 
 
 He said he wants a vote on bills that would prohibit people on the terror watch list from purchasing firearms and alert the FBI when those who have previously been on the list purchase guns. 
 
 “At the end of the day we need to ban assault rifles,” Nelson said. “This fellow [the Pulse gunman] had the equivalent of a souped-up M-16 military rifle.” 
 
 slemongello@orlandosentinel.com ||||| While the U.S. attorney in Orlando is remaining tight-lipped about whether he will ask a grand jury to investigate Omar Mateen’s widow or anyone else in connection with the deadly shooting at Pulse nightclub, veteran criminal defense attorneys say there is little doubt that he will. 
 
 A grand jury is the only tool federal prosecutors have to investigate felony crimes to determine whether charges should be filed against those involved, they explained. Unlike state attorneys, who are empowered to subpoena bank, phone and social media records and summon witnesses to testify, federal prosecutors have to go through a grand jury to build a case. 
 
 “The grand jury is the only vehicle the federal government has to collect information and compel the production of documents,” said West Palm Beach defense attorney Richard Lubin. 
 
 And, attorneys said, despite widespread speculation about the role Noor Salman played in her husband’s rampage that claimed 50 lives, including his own, they don’t expect the investigation into the deadliest shooting in the nation’s history will wrap up quickly. 
 
 “It’s just not a case you want to indict unless you’re sure you can get a conviction,” said West Palm Beach defense attorney Jack Goldberger. He said he knows Lee Bentley, the U.S. attorney for the Middle District of Florida, to be a meticulous prosecutor. 
 
 + Drew Angerer One local defense attorney who knows Lee Bentley, the U.S. attorney in Orlando, said don’t expect a fast decision. “He will ... read more Drew Angerer × 
 
 “He will move very deliberately and take his time before making any decisions,” Goldberger said. 
 
 Both he and Lubin disputed notions that Bentley is looking into the 30-year-old Salman simply for failing to report her husband’s plans to carry out the deadly attack, technically called misprision of a felony, punishable by a three-year prison term. Such charges are rarely filed and generally difficult to prove. 
 
 “Is she a principal?” Lubin said of the question Bentley is asking. 
 
 Conflicting statements Salman allegedly gave law enforcement that have been widely leaked to the press have been stunningly incriminating, attorneys said. 
 
 If, as has been reported, she drove Mateen, 29, from their home in Fort Pierce to the nightclub on previous occasions, helped him scout other locations or was with him when he purchased the weapons, she could be indicted as a co-conspirator. 
 
 “Then she could be an aider and abettor, and if she is, then she’s just as guilty as her husband was,” Goldberger said. 
 
 Fort Lauderdale defense attorney Bruce Zimet, a former federal prosecutor, said it is a time-honored rule that federal prosecutors seek an indictment for the highest-level crime available based on the evidence. In Salman’s case, it could be conspiracy to commit terrorism. 
 
 Zimet said he has been shocked at reports that she has made statements to FBI agents without an attorney present. While he and others said they expect her to refuse to testify before a grand jury, she can’t erase the past. 
 
 “Any statement she has given to law enforcement can be used against her,” Zimet said. “That’s why it’s so crazy for her to be talking from a technical and legal standpoint.” 
 
 He said there’s an axiom among prosecutors that Salman clearly was unaware of: “The only way a fish can get caught is if the fish opens its mouth.” 
 
 But, Lubin cautioned, there may be good reasons she is cooperating. “She may be giving them the names of others who are not cooperating,” he said. She along with bank and phone records and other documents could help prosecutors determine whether Mateen was a “lone wolf” or whether he was being directed by others. “There’s nothing standard about this case,” he said. 
 
 There is no evidence Salman, who was raised in California and met her husband online, has been detained. Her father-in-law, Seddique Mateen, who has held impromptu news conferences with reporters camped outside his Port St. Lucie house, said Thursday that she is no longer in Florida. She was captured by a news crew leaving the couple’s Fort Pierce home earlier this week wearing a white hoodie, but she gave no statement. 
 
 Attorneys said it is likely federal agents are watching her closely. If she makes any attempt to leave the country, there is no doubt she will be arrested, Goldberger said. 
 
 However, Lubin said, federal prosecutors want to avoid that because then the clock starts ticking. An indictment has to be filed 21 days after an arrest. If there is no indictment, a hearing would be held to allow a federal magistrate to determine whether there is probable cause to hold her in connection with the attack. 
 
 Prosecutors try to avoid a public airing of a case they are building, Goldberger said. “They very, very zealously protect whatever evidence they have gathered,” he said. 
 
 Further, he said, if they haven’t had time to collect bank records, phone messages and other documents they need, their case could fall apart. 
 
 That’s why they convene grand juries before making an arrest, Lubin said. “They need time to get their ducks in a row,” he said.
– A missed chance? Even without his name on a watch list, Orlando gunman Omar Mateen raised suspicions in at least one gun store in the weeks before he slaughtered 49 people at the Pulse nightclub. Robert Abell, co-owner of Lotus Gunworks in Jensen Beach, Fla., tells ABC that a man he now knows was Mateen tried to buy high-end body armor of a kind typically used by law enforcement and 1,000 rounds of ammo five or six weeks ago. He says Mateen asked strange questions and made staff uncomfortable, so they turned him away and informed the local FBI office about the would-be customer. Abell says there was a follow-up conversation with the FBI, but agents never visited the store—and without a sale, the store didn't have a name to give to investigators. In other coverage: Massacre survivor Miguel Leiva has shared video from the bathroom stall where he huddled for hours with around a dozen other people, some of whom had already been shot. It provides a glimpse of the terror inside the club in the hours before a SWAT team moved in. "It was really hot in there, the smell of blood and just dead bodies everywhere," Leiva tells CBS. The New York Times has interviews with several survivors, including people who suffered multiple bullet wounds. Angel Colon has a chilling account of trying to play dead as the gunman shot wounded people on the floor. Law enforcement sources tell CNN that Mateen texted his wife hours after the attack began, asking her if she had seen the news. She told him she loved him and tried to call several times, the sources say. The Miami Herald reports on a mysterious incident from Mateen's past: His firing from a job in a state prison midway through his training, apparently over an incident involving serious misconduct. The Orlando Sentinel reports on President Obama's visit to Orlando Thursday, where he met with victims' relatives in private. "Today, once again, as has been true so many times before, I held and hugged grieving family members and parents," Obama told reporters afterward. "And they asked, 'Why does this keep happening?'" The Palm Beach Post looks at the possible charges against Mateen's wife, Noor Salman, and at why an indictment could take a long time. (There were moving scenes when JetBlue fliers realized a fellow Orlando-bound passenger was mourning a grandson killed in the attack.)