(CNN) Ahmed Fahad was a computer whiz kid in Bangladesh when Fahim Saleh agreed to hear his pitches for book-sharing and dating apps.
Saleh, a tech entrepreneur who was then helping launch the Bangladeshi ride-sharing start-up Pathao, gave Fahad a coding assignment to return within 24 hours.
"I expected him to not ... even talk to me," Fahad recalled. "But he did. He listened to my idea. He didn't care that I was 17 and still in high school."
Fahad is now a 22-year-old vice president at Pathao.
Saleh, who most recently founded the Manhattan venture capital firm Adventure Capital, was well known for his support of fledgling techies like Fahad.
"He genuinely liked doing these things for young people," Fahad said. "He took a bet on me. It changed my life."
Saleh, 33, was killed in his Manhattan apartment on Monday, according to police.
His executive assistant, Tyrese Haspil, 21, has been charged with second-degree murder in connection with Saleh's decapitation and dismemberment.
Haspil, who handled Saleh's finances and personal matters, was in his late teens when the entrepreneur hired him, according to a law enforcement official with knowledge of the investigation.
"When I first heard about his death, I was in denial," Fahad said. "I honestly expected him to come out at any moment and say, 'This is all a joke. This is all a big prank.' Because that's the type of guy he was."
Saleh was himself in high school when he founded PrankDial.com, a website for prerecorded prank phone calls that, he wrote in 2018, had generated over $10 million since its start.
Saleh was found dead on Tuesday afternoon in the living room of his luxury condo on the Lower East Side, police said. His cousin had gone to check on him. His head and limbs were severed.
Haspil allegedly assaulted Saleh with a Taser before killing him one day earlier, NYPD Chief of Detectives Rodney Harrison said. Saleh had just stepped out of an elevator that went straight to his seventh-floor apartment.
Saleh was last seen in surveillance video getting into the elevator with a masked man dressed in all black, according to a law enforcement official.
The assistant allegedly owed his boss tens of thousands of dollars, and was on a repayment plan, the official said.
An autopsy showed Saleh died from five stab wounds to the neck and torso, according to the criminal complaint.
Surveillance video from a Manhattan hardware store on Tuesday morning captured Haspil purchasing an electric saw and cleaning supplies, which were later discovered near Saleh's dismembered and decapitated torso, the complaint said.
When Saleh's cousin buzzed his condo later Tuesday, the assistant was allegedly dismembering his body with the saw and fled, according to a law enforcement official.
Haspil was arrested in Manhattan on Friday morning.
CNN has sought comment from Haspil's attorney. He was arraigned early Saturday and remanded in custody.
Saleh was born in Saudi Arabia to Bangladeshi parents. He grew up in upstate New York and had a computer science degree from Bentley University in Massachusetts.
"The headlines talk about a crime we still cannot fathom," his family said in a statement this week. "Fahim is more than what you are reading. He is so much more. His brilliant and innovative mind took everyone who was a part of his world on a journey and he made sure never to leave anyone behind."
Saleh was a boy when he built his first website. It was called Salehfamily.com, which family members visited when his parents had parties, according to a Radiche.com article in 2016.
Growing up, Saleh would sit at home in his pajamas creating sites with ads that generated revenue.
In his teens and while at Bentley, Saleh founded and sold websites that catered to young people.
"I would stay up super late ... and would be worried my Dad would catch me," he told Radiche. "He thought it would hinder my schoolwork, which it didn't. Then, I got my first paycheck from Google for $500 as a teenager and showed it to my Dad. He was like, 'Okay, let's open an account.'"
In 2015 Saleh joined others to launch Pathao. The app offers ride sharing and food delivery. It would become one of the fastest growing start-ups in Asia.
Fahad, recalling his introduction to Saleh in high school, spent all night working on that 24-hour coding challenge.
After ghosting Fahad for several days -- "I think it was just his way of testing persistence," Fahad said. -- Saleh hired him and gave him flexible hours so he could finish high school.
"It was the biggest chance anyone has ever taken on me," said Fahad, who is Pathao's vice president of product.
"The Fahim Saleh that a lot of people here knew was a doer, really. A builder. Most entrepreneurs come up with ideas. He put his money where his mouth was. He backed people with both money and advice and made things happen," Fahad said.
Fahad remembered a friend from Bangladesh who was suffering bouts of loneliness while studying at Cornell University.
"He messaged Fahim one day," Fahad said. "Fahim said, 'No problem, dude. Come over and we'll chill.' Fahim took him out to dinner and hung out with him."
Hussain M. Elius, a co-founder and CEO of Pathao, told The Daily Star newspaper in Bangladesh that Saleh "believed in the potential for technology to transform lives in Bangladesh and beyond."
"He saw the promise in us when all we had was a common purpose and a shared vision," Elius said.
Saleh was CEO of Gokada, Nigeria's motorcycle ride-hail company, which launched in 2018.
On Medium, where Saleh blogged regularly, he called his founding of Gokada "one of the most out there things" he had ever done. His limited knowledge of the country's transportation system at first turned off Nigerians he tried to recruit for his start-up.
The company raised over $5 million and hired over 800 drivers, but Gokada hit a roadblock earlier this year when Lagos banned commercial motorcycles.
Saleh filmed an impassioned plea for lifting the ban on behalf of his employees.
"I'm never going to give up because that's the true attribute of an entrepreneur, never giving up," Saleh said in a YouTube video in February.
"Entrepreneurs are the ones that really change countries, that really change cities. They're the ones who bring the vision. They're the ones who bring the passion," he said.
The company pivoted to delivery and worked toward launching a boat hailing service, he told CNN in February.
"When I was in Lagos I saw that the waterways were empty," Saleh said. "So, in 2019, I ordered two boats literally on Alibaba. They are 24 passenger boats with a bathroom enclosed."
Fahad's last contact with Saleh was about a month ago.
"Yo, thanks for hiring me back in 2015," he wrote via Instagram.
"You've come a long way," Saleh responded.