The girlfriend of the shooter who killed 59 people in Las Vegas on Sunday has returned to the United States from the Philippines in what investigators hope would shed light on what drew the retiree to commit his rampage. Marilou Danley, who US authorities have described as a “person of interest” in the investigation, will be interrogated by the Federal Bureau of Investigation (FBI) about the massacre. A police official in Manila and a law enforcement official in the United States, both speaking on condition of anonymity, told Reuters that Danley left the Philippines unescorted but was met by FBI agents in Los Angeles. Sheriff Joseph Lombardo said that "we anticipate some information from her shortly," and said he is "absolutely" confident authorities will find out what set off Paddock. The US source said Danley was not under arrest but that the FBI hoped she would consent to be interviewed voluntarily. The police official in Manila said Danley’s trip back to the United States “was coordinated with FBI authorities” and that she was returning to clear her name of any involvement in the deadliest mass shooting in modern US history. Stephen Paddock, her live-in companion who killed himself moments before police stormed the Las Vegas hotel suite he had transformed into a sniper’s nest on Sunday night, left no clear clues about why he staged his attack on an outdoor concert below the high-rise building. Retired FBI profiler Jim Clemente speculated that there was "some sort of major trigger in his life — a great loss, a breakup, or maybe he just found out he has a terminal disease." Clemente said a "psychological autopsy" may be necessary to try to establish the motive. If the suicide didnt destroy Paddocks brain, experts may even find a neurological disorder or malformation, he said. He said there could be a genetic component to the slaughter: Paddocks father was a bank robber who was on the FBIs most-wanted list in the 1960s and was diagnosed a psychopath. Danley, according to public records and police, shared Paddock’s condo in a retirement community in Mesquite, Nevada, about 90 miles (145 km) northeast of Las Vegas. The Philippine police official said authorities in Manila were told that Paddock used identification belonging to Danley, who has an Australian passport, when checking in to the Las Vegas hotel. Investigators are also examining a $100,000 wire transfer that Paddock sent to an account in the Philippines that appeared to be intended for Danley, a senior US homeland security official told Reuters on Tuesday. The official, who has been briefed regularly on the probe but spoke on condition of anonymity, said investigators were working on the assumption that the money was intended as a form of life insurance payment to Danley. The official said US authorities were eager to question Danley about whether Paddock encouraged her to leave the United States before going on his rampage. Danley, an Australian citizen aged 62 who is reported to have been born in the Philippines, has a daughter who lives in Los Angeles, said the New York Times. President Donald Trump will meanwhile visit Las Vegas on Wednesday to soothe the stricken city. His trip to Las Vegas will be the first time he has had to deal directly with the tragic aftermath of deadly gun violence that has routinely claimed hundreds of lives in recent years. “It’s a very horrible thing even to think about,” Trump told reporters on Air Force One on Tuesday. “It’s really horrible.” “He’s a sick man, a demented man. A lot of problems, I guess. We are looking into him very, very seriously. But we’re dealing with a very, very sick individual,” Trump said of Paddock on Tuesday. Trump has had mixed success in the traditional role of “consoler-in-chief.” He inflamed racial tensions in the aftermath of a white-supremacist rally in Charlottesville, Virgina, and he has struggled to strike the right tone in responding to hurricane devastation in Puerto Rico. Visiting Puerto Rico on Tuesday, Trump said jokingly that the recovery from Hurricane Maria there was blowing the US budget “a little out of whack.” He spent most of his day meeting with people charged with responding to the crisis than with people affected by it. The Las Vegas shooting has reignited a debate in Washington and across the country about whether more gun control legislation might have prevented what happened. Republicans who control the US Congress have shown little inclination to respond to Democratic appeals for gun measures, although momentum appears to have slowed for legislation that would make it easier to buy gun silencers. On the campaign trail last year, Trump aligned himself with gun rights advocates who consider the US Constitution’s Second Amendment right to bear arms sacrosanct. Asked on Tuesday whether it was time to debate gun control measures, Trump said: “Perhaps that will come. But that’s not for now.”