Nearly a week after the worst mass shooting in modern US history, there's still no answer.

A shooter's reasons, however sick and twisted, usually become clear within a day or two. A suicide note, a manifesto, a series of social media screeds, a phone call -- even police reports and court dockets can provide insight into what drives a warped mind to commit such a violent act.

Usually, someone close knows something or realizes, in retrospect, that they missed the warning signs.

But 64-year-old Stephen C. Paddock flew low under the radar. He avoided interaction with many of the people around him, and his manner was direct and brusque. He was known to stay up all night gambling, but it was as if he was the only reveler at his own party.

As authorities dive deep into Paddock's computers, itinerant high-rolling lifestyle and finances, they still don't have an answer.

They still don't know why.

Stephen Paddock

Clark County Undersheriff Kevin C. McMahill seemed almost apologetic Friday afternoon when he told reporters that despite running down some 1,000 leads, investigators still haven't come up with "credible information" concerning Paddock's motive. Chasing down all those leads "helped create a better profile into the madness of this suspect," McMahill said, but "we still do not have a clear motive or reason why."

The previous evening, Sheriff Joe Lombardo summed up the mystery man this way: Paddock "spent decades acquiring weapons and ammo and living a secret life, much of which will never be fully understood."

Even the people closest to the shooter are struggling to understand why, on a Sunday night on the Las Vegas Strip, Paddock perched in a posh hotel suite at the Mandalay Bay Resort and Casino and fired round after round at a crowd of 22,000 country music fans 32 stories below.

"Steve was a private guy -- that's why you can't find any motive," said his younger brother, Eric, who spoke for half an hour with reporters Tuesday in the driveway of his home in Florida.

Eric Paddock's anguish was there for all to see as he struggled to wrap his head around the cold, hard fact that the affluent, successful big brother who was "fun to hang out with" rigged a sniper's nest in a hotel suite and shot 58 strangers to death and wounded hundreds more.

People scramble for shelter at the Route 91 Harvest country music festival. The shooter's motive remains a mystery.

His brother liked country music, Eric Paddock said. So it makes little sense that he chose others who shared that enthusiasm as his targets.

'No types of clues'

For now, Eric Paddock says, the lack of a clear motive makes the nightmare his brother caused all the more disturbing.

"There are no types of clues, that's the problem," Paddock told the clutch of reporters in his driveway. "This is what everybody is scared about right now. If Steve could do this, we are all in deep (expletive) because there's nothing there. I hope to hell that they find when they do the autopsy that there's a tumor in his head or something because if they don't, we're all in trouble."

Occasionally wiping tears from his eyes and insisting, "I'm not a crying kind of guy," Paddock offered his own theory:

Paddock's brother Eric said, "There are no types of clues" to his brother's actions. "That's the problem."

"Something horrible happened to my brother and whatever happened to him in his head, it made him go over the edge like this," he said.

He took comfort in news a reporter had texted him that day -- that Paddock wired $100,000 to his girlfriend, Marilou Danley, in the Philippines before the massacre.

"The clue that reveals Steve," he said, "is that he transferred $100,000 to the Philippines to take care of Marilou." He said that was the brother he knew.

"As Steve was cratering into this hell, he wanted to take care of Marilou."

Danley, for her part, thought Paddock was through with her, she said through her lawyer. "I was worried that first, the unexpected trip home, and then the money was a way of breaking up with me. It never occurred to me in any way whatsoever that he was planning violence against anyone."

And that, in itself, says plenty about the cipher that was Stephen Paddock. He gave away so little of himself personally that initially the two people closest to him had opposite interpretations of why Paddock had sent his girlfriend off on a trip.

Marilou Danley said through her lawyer she thought Paddock sent her to the Philippines to break up with her.

One thing Marilou Danley and Eric Paddock apparently can agree on, though: Steve Paddock was a private man who spent money -- lots of it -- on the people he loved.

"I knew Stephen Paddock as a kind, caring, quiet man," Danley said in her statement. "I loved him and hoped for a quiet future together with him. He never said anything to me or took any action that I was aware of, that I understood in any way to be a warning that something horrible like this was going to happen."

"If you were Steve's friend, he would spend money on you," his brother said. He recalled a visit during which Paddock took him out to eat "thousands of dollars of sushi," all comped by a casino hotel where he gambled. He got the high-roller treatment -- not bad for a bank robber's kid from suburban Los Angeles.

Son of a bank robber

Stephen was the oldest of four Paddock boys raised by a single mother after their father, Benjamin Hoskins Paddock, was hauled off to prison for "robbing banks with a machine gun," as Eric Paddock put it.

Stephen was 7 at the time. His father was considered by law enforcement to be a dangerous psychopath with suicidal tendencies and used several aliases and nicknames, the most colorful of which was "Chromedome."

The elder Paddock twice escaped from prison, earning a spot on the FBI's Most Wanted list from June 1969 until May 1977. He was captured the following year, served out his sentence and returned to Oregon, where he died a few years ago.

Benjamin Hoskins Paddock was a bank robber who went to prison when his son Stephen was 7.

Their mother, now in her 90s, told her sons their father was dead, Eric Paddock has said. He doubts the man had much influence on his brother beyond his absence. It left the boys with a story to tell, but that was the extent of it, he said.

Stephen Paddock attended high school in the San Fernando Valley and graduated from California State University, Northridge with a degree in business administration in 1977. He married that July and already was working as a mail carrier for the US Postal Service. He'd started there as a temp as he completed his studies and went full time before he graduated.

Paddock left that job to work for the Internal Revenue Service. He later became an auditor for the federal Defense Contract Agency, leaving that job in September 1985.

He remarried at about that time. His first marriage lasted just over two years and when the marriage ended, she got the Honda Civic and he held onto the Pontiac Firebird, a new boat and his federal pension.

After the divorce, he began building passive income by investing in real estate, especially by fixing up rundown apartment buildings. He still had a day job, working during the mid to late 1980s for a company that would become part of Lockheed Martin.

His second marriage also ended in divorce in 1990.

After that, Paddock appears to have left Southern California, moving to Texas, Florida and Nevada. He purchased guns and property in four states, public records show. Besides his homes in Reno and Mesquite, Paddock has bought and sold at least nine other properties since the 1980s, some of which he owned with family members.

He met Danley after he started buying up properties around Reno, Nevada, in 2012. She worked as a hostess for high rollers at Club Paradise at the Atlantis Casino Resort Spa.

Some people, including Eric Paddock, said they were a devoted couple, but others sensed a cold disconnect between them.

Just another gambler

For someone who led such an adventurous life, Paddock didn't seem to like other people much. If he was often generous with friends and loved ones, he was taciturn with others.

Real estate agents said he paid cash for the Mesquite house. Neighbors seldom saw him, and when they did, he rarely waved. He erected a privacy fence, telling a neighbor that he didn't want to see anybody and he didn't want anybody seeing him.

A stylist who occasionally trimmed his hair said Paddock often came in as she opened in the mornings. He'd say he'd been gambling all night and reeked of alcohol.

About two months ago, he told the stylist he was going to send his girlfriend, Danley, to the Philippines for a family visit. Danley said through her lawyer that she found out about the trip just weeks, not months, beforehand. She said it was a surprise.

Paddock reportedly rented out hotel rooms or condos overlooking other events in Chicago, Boston and Las Vegas before checking into the Mandalay Bay's hotel on Monday, September 25, six days before the shooting.

Speaking reluctantly and anonymously out of fear for their jobs, several hotel employees said they recognized Paddock as a regular who favored Asian restaurants. He ordered two entrees -- lemon chicken and scallops with snow peas -- at a restaurant in the hotel on Saturday night, but dined alone.

He wasn't chatty, but they knew him as a good tipper.

He favored a private suite reserved for high-bet video poker players, tucked away from the main casino floor, behind low walls lined with slot machines.

"He just seemed like another gambler," said one employee. "Now I look at everybody and wonder."