He killed his wife, Subasari, 39, sons Krishna, 19, Ganesh, 12, Arjuna, 7, mother-in-law, Indra, 69, before killing himself in San Fernando Valley, 20 miles northwest of Los Angeles.
The tragedy has sent shockwaves through the US, not just among Indians settled there. As no end seems in sight to the turmoil in the markets, many are worried whether Rajaram's suicide could trigger more such desperate acts, it is feared.
Rajaram, who once made more than $1.2 million in a London-based venture fund had lost his job. His luck playing the stock market ran out. On Sept. 16, he bought a gun. He wrote two suicide notes and a last will and testament. And then, sometime between Saturday night and Monday morning, he killed his wife, mother-in-law and three sons, and took his own life, Los Angeles Times reported.
"This is a perfect American family behind me that has absolutely been destroyed, apparently because of a man who just got stuck in a rabbit hole, if you will, of absolute despair, somehow working his way into believing this to be an acceptable exit," said LAPD Deputy Chief Michel Moore. "It is critical to step up and recognize we are in some pretty troubled times."
In a letter addressed to police, Rajaram blamed his actions on economic hardships. A second letter, labeled "personal and confidential," was addressed to family friends, the third contained a last will and testament, Moore said.
The letter to police voiced two options: taking his own life, or killing himself and his entire family. "He talked himself into the second strategy," Moore said. "That that would be the honorable thing to do."
Authorities believe Rajaram killed his family and himself after seeing his finances wiped out by the stock market collapse, according to a source familiar with the case, who spoke on condition of anonymity because the investigation is ongoing.
Concern about the family's welfare began Monday morning when Rajaram's wife, 39-year-old Subasri, did not show up for her carpool. Friends went to the house in the 20600 block of Como Lane, only to find it strangely quiet. The morning newspaper lay in the frontyard. The family's two cars, a Suburban and a Lexus SUV, were parked in the driveway.
When police entered the home in the gated, Spanish-style community, they first found the gunman's mother-in-law, Indra Ramasesham, 69, dead in a downstairs bedroom. His wife and three sons - Krishna, 19, a sophomore at UCLA majoring in business economics, Ganesha, 12, and Arjuna, 7, all named after Indian gods and warriors - were discovered in various upstairs bedrooms, all shot in the head, some with multiple gunshot wounds.
Their father was found dead in a bedroom with Ganesha and Arjuna, the gun still in his hand, police said.
The Rajarams had lived in the upscale Sorrento neighborhood of Porter Ranch for a couple years in a 2,800-square-foot rented house. The landlords, another Indian couple, said that the family paid their rent on time and that there were no indications of trouble.
Neighbors in the Northridge neighborhood where the family previously lived said they were well-liked and enjoyed entertaining guests. Except for one night when residents heard a man screaming for hours, the family seemed content for the nine years they lived there.
"He loved those kids more than any man I've seen love his sons," said next-door neighbor Sue Karns.
But Karthik Rajaram, who held an MBA from UCLA, was a hard-driving businessman. He was involved in several financial ventures. Between his home sale and another lucrative investment, he should have had a pile of cash.
A 2001 article in The Daily Telegraph of London, under the headline "Bust, but big bucks for the big boys," called Rajaram a "winner" in a deal for NanoUniverse, a Los Angeles- and London-based venture fund taken public on the London Stock Exchange.
For a 12,500-pound investment, Rajaram, one of the company's founders, received 875,000 pounds - or about $1.2 million in 2001 dollars - after a voluntary liquidation, the newspaper reported.
He also sold his house in 2006, a calculated decision even though his wife, a bookkeeper at a pharmacy, did not want to move, their former neighbors said.
He sold the house for $750,000, making a sizable profit on a home the couple purchased in 1997 for $274,000.
"The market was going down and he wanted to get out before the bottom dropped out," Karns said. "I talked to him last December and he said, 'I feel I did a good thing by selling when I did.' "
It is unclear how Rajaram invested the cash since then and how he lost it.
He had some behavioral problems," Robinson said. "He wasn't reliable. . . . He was not an emotionally stable person. It was a real problem and would affect any business he was involved in."
The two had also worked together in the Century City office of PriceWaterhouseCoopers and Robinson recalled Rajaram as being "a very smart guy," who he believed posted a perfect score on his business school entrance exam.
Although Karns and her husband said they liked Karthik Rajaram and were stunned by the news, they said he was "very high-strung, very intense."
"The man was never relaxed," Sue Karns said.
In the Porter Ranch neighborhood, next-door neighbor Kinda Almukaddem said she had rarely spoken to the family since they moved in a couple of years ago. But in the last two weeks, Karthik Rajaram visited her twice asking whether she would be home this past weekend. He urged her to keep her side windows shut because he had heard of burglaries in the area.
Rajaram seemed nervous - shaking, pacing and taking notes on a notepad as he spoke to her, she said.
"He noticed my side windows were open, the side that my house shares with him," she said. "Now, come to think of it, I think he was trying to have me close my windows on that side so I wouldn't hear anything."
Police said nobody reported hearing gunshots or anything out of the ordinary.
But on Monday, the neighborhood was far from normal, with police leading convoys of media into the gated community. Children at nearby Alfred B. Nobel Middle School, where 12-year-old Ganesha Rajaram was a seventh-grade honors student, were sent home with notes informing their parents of the news.
"This one will shake people to the core," Principal Robert Coburn said. "When you think about it, all kids have a mom and dad. And if a father can do this to his kids, it's very scary."