The gunman who massacred 49 people at a popular gay nightclub in Orlando, Fla., searched on social media for news of his murderous rampage during the attack, investigators have found.
Apparently using his smartphone, Omar Mateen searched on Facebook for "Pulse Orlando" and "shooting" during his three hour early morning attack on patrons inside the Pulse nightclub.
And moments before he opened fire, Mateen posted four updates on Facebook about his ostensible political agenda, issuing threats and demands similar to those he later made to the emergency 911 operator.
"America and Russia stop bombing the Islamic state..I pledge my alliance to [Islamic State leader] abu bakr al Baghdadi..may Allah accept me," he wrote.
He also wrote: "The real muslims will never accept the filthy ways of the west" and "You kill innocent women and children by doing us airstrikes..now taste the Islamic state vengeance."
The final post on Facebook reads, "In the next few days you will see attacks from the Islamic state in the usa."
The Internet searches gleaned by investigators suggest Mateen had ample time on his hands during lulls in the slaughter. Witnesses have said he even stopped to wash his hands and use the hot air hand drier at one point.
Despite Mateen's posts, FBI officials say they have found no evidence of a larger plot, and no intelligence indicates another imminent planned attack.
Nor have they uncovered evidence indicating that Mateen had any previous contact with or support from Islamic State or other international terrorist groups.
They believe Mateen was self-radicalized on the Internet over a period of several years and decided only recently to embrace Islamic State.
FBI analysts have determined that Mateen watched online jihadist sermons since at least 2012 and more recently had downloaded jihadist material to his laptop computer, including grisly videos of beheadings of captives by militants.
Scrutiny of Mateen's computer hard drive by the FBI has found no documents written by Mateen that explain why he chose the Pulse nightclub for his attack, or why he chose to go to the club at 2 a.m. Sunday.
Mateen's Facebook posts were revealed in a letter to Facebook Chief Executive Mark Zuckerberg from Sen. Ron Johnson (R-Wis.), chairman of the Senate Committee on Homeland Security and Governmental Affairs.
The letter asked Zuckerberg to provide Mateen's Facebook activity logs, timeline information, messages, photos and posts. It also asked for the company to brief the committee.
Facebook has received the letter but has not responded yet, a spokesperson wrote in an email. The committee request is not a subpoena, and the company is not required to comply.
Committee staff found that Mateen also used Facebook in May to search for information on the married couple who shot and killed 14 people at a holiday party on Dec. 2 in San Bernardino.
On June 4, Mateen apparently entered a search with the words: "Baghdadi Speech," referring to the Islamic State leader in Iraq and Syria.
Johnson sent a similar letter to the private security company G4S Secure Solutions to request Mateen's employment records
G4S hired Mateen as a security guard in 2007 and assigned him to the St. Lucie County Courthouse. In the spring of 2013, alarmed coworkers told authorities that Mateen had claimed to have family members in Al Qaeda and had made threats.
The FBI launched a 10-month investigation of Mateen that included use of confidential informants, eavesdropping on his communications and surveillance of his movements.
The FBI closed its probe in March 2014 and took Mateen off the terrorist watch list after concluding that he was full of bluster.
During that period, G4S transferred him to a job at a nearby gated community of luxury homes and a golf course. He completed his usual shift in the gatehouse there without incident Saturday before he drove north to the Pulse nightclub.
The investigation into his attack there has hit at least one roadblock.
FBI agents have had difficulty accessing data stored on the cellphone Mateen used during the massacre because it was damaged by water and blood, a law enforcement official said.
But technicians are putting the device through a drying process and are confident they ultimately can recover phone numbers, texts, photos and other data, said the official, who spoke on condition of anonymity to discuss progress in the investigation.
Another problem: Mateen's wife, Noor Zahi Salman, has changed her story in interviews with the FBI over the last two days, according to a U.S. law enforcement official who spoke on condition of anonymity to discuss the investigation.
"Her story has been very fluid, and we are still evaluating it," the federal official said. "It has evolved, but not in a simple or straightforward way."
Salman at first told investigators that she had accompanied her husband to purchase ammunition at a gun store and to visit Pulse, the official said.
She also initially told them that she had been generally worried that he might do something to harm others.
More recently, she has told investigators that she specifically warned her husband on Saturday not to commit an attack later that night.
Salman submitted to a polygraph examination during one of the interview sessions, another law enforcement official said. It's still unclear which of her stories is true, the official added.
Investigators use polygraphs to try to determine whether someone is lying, and as leverage to pressure witnesses or suspects to be truthful in later interrogations. Polygraph results are not admissible in court.
If Salman had knowledge of the attack, her failure to notify authorities could lead to an array of federal criminal charges, potentially including conspiracy to commit murder.
As part of the investigation, federal prosecutors and agents are using a grand jury in Orlando to issue subpoenas to obtain records, the official said.
Those could include employment and telephone records, as well as financial and credit card statements that may help investigators understand his background and movements, contacts and motivation.
No testimony has been taken and there are no plans yet to present witnesses.
No charges are imminent, the official said, because agents are in the early stages of gathering evidence and feel no pressure to rush the investigation.
MORE ON ORLANDO SHOOTING
1:38 p.m.: This article was updated with new information about the investigation and Omar Mateen's Facebook posts. .
7:47 a.m., June 15: This article was updated with new details of the FBI investigation.