Police have identified Stephen Paddock as the gunman who opened fire on concertgoers from a hotel room in Las Vegas, killing at least 58 people and leaving more than 500 wounded in the deadliest mass shooting in modern U.S. history.

Paddock, 64, began shooting from two windows on the 32nd floor of the Mandalay Bay Resort and Casino just after 10 p.m. local time Sunday evening, police said. A SWAT team found Paddock dead in his hotel room and officials believe he killed himself.

Police said Paddock had at least 23 firearms in his hotel suite. He had been staying in the room since Sept. 28. They said another 19 firearms, thousands of rounds of ammunition, explosives and electronics were found at his home at a retirement community in Mesquite, Nevada, about 75 miles northeast of Las Vegas. Police also searched a two-bedroom home Paddock owned in a retirement community in Reno.

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CBS News has learned that Paddock recently added to his stockpile of weapons. A law enforcement source close to the investigation said Paddock recently purchased some of the firearms and ammunition, CBS News justice and homeland security correspondent Jeff Pegues reports. The timing of the purchases are relevant as investigators try to pin down a motive for the attack.

FBI Special Agent in Charge Aaron Rouse said in a press conference Monday morning that the bureau had found "no connection with an international terrorist group." The motive was still under investigation.

A law enforcement source tells CBS News senior investigative producer Pat Milton that Paddock may have planned an earlier attack at a concert in Las Vegas in September. Investigators are looking at whether he may have first had his sights on the "Life is Beautiful" festival, which featured several concerts including a performance by Chance the Rapper.

The source, who was briefed on the police investigation, told Milton that Paddock tried to get a room at the Ogden Condo Hotel and another hotel in downtown Las Vegas, but the specific suites he requested were booked. The source speculated that Paddock may have been seeking rooms that were strategically located to the festival to launch an attack.

Stephen Paddock lived in Mesquite with his 62-year-old girlfriend, Marilou Danley, who was overseas when the shooting unfolded. Law enforcement officials say they do not believe she was involved in the shooting, but will question her about Paddock's behavior when she returns to Nevada.

Danley is believed to still be in the Philippines, a law enforcement source said. Authorities have located her but it is unclear how cooperative she has been or what the degree of contact with her has been, the source said. Danley was scheduled to return to the U.S. possibly within the next day or so. As of Tuesday afternoon, it was not known whether she had already left the Philippines.

Another law enforcement source said Paddock transferred more than $10,000 into a bank account in the Philippines in recent weeks, Milton reports. It is unclear who the payment went to and if it went to Danley or her family who lives in the Philippines.

The source said there have been numerous suspicious activity reports involving large cash transfers overseas flagged against Paddock, apparently by FinCEN, the Financial Crimes Enforcement Network. The time period of the transfers is unclear.

Paddock had no criminal record beyond a routine citation several years ago that was handled in court.

Eric Paddock, the gunman's brother, spoke to reporters outside his home Monday morning. He described Danley as kindly and said she sometimes sent cookies to his mother. Eric Paddock said he is "horrified" and "dumbfounded" by his brother's actions.

"No religious affiliation. No political affiliation. He just hung out," Eric Paddock said.

"He had a couple of guns but they were all handguns, legal," he told reporters. "He might have had one long gun, but he had them in a safe."

Two officials familiar with the investigation told the Associated Press that Stephen Paddock had two devices that could have allowed semi-automatic weapons to function as fully automatic ones, the news service reported Tuesday. The devices, known as "bump-stocks," use the recoil from firing the gun to continually "bump" against the trigger, firing off more rounds, according to the AP.

Eric Paddock said his brother was a multimillionaire who made much of his money investing in real estate. He said his brother was an accountant for many years and he wasn't aware of him having financial difficulties.

In an interview with the AP, Eric Paddock said his brother was "not a normal guy" and last had contact with him in September in a series of text messages. He said Stephen Paddock played "high stakes video poker" and once texted him a picture of him winning $40,000 on a slot machine.

Eric Paddock also confirmed to multiple outlets that his and Stephen's father was Benjamin Hoskins Paddock, a notorious bank robber who was on the FBI's most wanted list for eight years after escaping from prison in 1969. He once tried to run down a federal agent with his car and was serving a 20-year sentence for a string of robberies in Phoenix when he escaped.

An FBI poster about the elder Paddock at the time called him "armed and very dangerous" and he remained on the bureau's list until 1977. He died in 1998.

President Trump called the shooting "an act of pure evil" in remarks Monday morning. He hailed first responders and said that the FBI and Department of Homeland Security are working with local officials in the investigation. He did not refer to the attack as an act of terrorism.

Investigators are still trying to determine Paddock's motive. The Islamic State of Iraq and Syria (ISIS) claimed responsibility for the shooting, but offered no proof. U.S. officials tell CBS News there are no signs that Paddock had ties to radical Islamic groups or showed signs of being radicalized. Police obtained a search warrant for his home in Mesquite and are securing the site, a law enforcement source said.

Records show Paddock moved to Mesquite in June 2016. He had previously lived in Reno, Nevada, from 2012 to December 2016, and was listed at an address in Melbourne, Florida, from 2013 to 2015. Paddock moved between Texas and California from the late 1990s to the early 2000s.

The AP reports Paddock lived in Mesquite, Texas, from 2004 to 2012. Lt. Brian Parrish told the AP that property records showed Paddock lived in the Dallas suburb during that time period and possibly longer. He said Paddock owned at least three rental properties in the area, and police found no indications of interacting with Paddock while he lived there.

Paddock worked for a "predecessor company" of defense contractor Lockheed Martin from 1985 to 1988, the company said. Lockheed said it was cooperating with authorities to provide details of his employment. The company declined to say what position Paddock held.

Court records show Paddock sued the Cosmopolitan Hotel and Resorts on the Las Vegas strip in 2012, alleging he suffered substantial injuries when he slipped and fell in the hotel. The case was dismissed by both parties, indicating they had reached a settlement.

Paddock was a licensed hunter and had a license to fly a small plane, records show.