The brother of the Las Vegas shooter spoke again to reporters again Tuesday in the wake of the deadliest mass shooting in modern American history.

Eric Paddock, speaking outside his Orlando home, said he was having trouble processing "the horror story" after his brother, Stephen Paddock, opened fire on concertgoers in Las Vegas Sunday night, killing 58 people and injuring more than 500 people.

"Steve took care of the people he loved. He helped make me and my family wealthy. He's the reason I was able to retire. This is the Steve we know, we knew. The people he loved and took care of," Eric Paddock said.

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In the rambling, emotional interview, Eric Paddock spoke of his family's life and their hardships. He said Stephen Paddock helped make their mother's "retirement very comfortable."

"My mom was born in the Depression, she had a tough life her husband was an a******. She raised four kids on a secretary salary and some of us weren't great kids -- we were bad kids at some level. We grew up poor in San Fernando Valley," he said. (Their father, he acknowledged Monday, was a bank robber who spent years on the FBI's Ten Most Wanted list in the 1960s and 70s.)

"My heart is destroyed, for all these people, but I can't tell you why Steve did what he did," Eric Paddock said.

He said he couldn't understand what drove his brother to fire on thousands of concertgoers through two windows on the 32nd floor of the Mandalay Bay hotel.

Eric Paddock said that his brother was not insane or crazy and described him as a highly "intelligent" and "successful" person.

He said it was fun to be friends with his brother because "he was a rich guy" who hung out in casino hotels but didn't have a lot of friends. He called him an independently wealthy man who basically gambled for a living. In one trip to Las Vegas with his son, Eric Paddock said his brother spent "thousands of dollars" worth of sushi.

"If you were Steve's friend, he would spend money on you," he said.

Investigators are still trying to find a motive in the attack. Eric Paddock said he believes something must have happened to his brother in recent months that drove him to kill others. He said he's praying investigators find answers.

Investigators believe the gunman may have been planning an earlier attack on a different Las Vegas concert in September, a law enforcement source told CBS News investigative producer Pat Milton.

"He didn't plan this for 35 years. This happened to my brother -- whatever caused him to do this -- it happened over the course of months. And here is what I say to the people -- maybe no one will ever understand Steve," Eric Paddock said.