Given his ostentatious displays of wealth and the unusual hours he kept, neighbours assumed Karim Baratov was making his money on the Internet somehow.

Teenagers in his neighbourhood in Ancaster, a suburb of Hamilton, knew him from social media, where he had thousands of followers, and told their parents they heard he had sold an Internet business for millions of dollars.

He lives in a typical suburban home on a relatively quiet street populated mainly by young families. Small, discreet security cameras surround the house, watching the door and driveway and other approaches.

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On Tuesday, a police car was parked outside the house on Chambers Drive all day. On Wednesday, the U.S. government announced that the self-described high-school drop-out who had a taste for fast cars had just been arrested in connection with an alleged Russian-sponsored hack of e-mail accounts.

Mr. Baratov, 22, a dual citizen of Canada and Kazakhstan, was photographed by The Globe and Mail last summer at a Supercar Sunday event driving an Aston Martin DB9, which according to auto websites can sell for more than $200,000 and can accelerate from 0 to 100 kilometres an hour in a little more than four seconds.

On Chambers Drive, his fast driving was a source of friction, as it made a lot of noise, woke people and frightened parents and dog owners. "You knew to hold your dog close when you heard it," one man said. But it made keeping track of Mr. Baratov's movements relatively easy, neighbours added. If the street was quiet for a few days, Mr. Baratov was away. (A sign warning drivers to watch their speed was erected near the house last summer.)

"If you're in bed at night, you know when he has come home," said Kerry Carter, a neighbour who lived two doors away.

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Ms. Carter edits Mystery Weekly magazine, and said she was intrigued by the new neighbour when he bought the house a few doors down from hers about two years ago. He kept mostly to himself, she said.

"He's kind of a quiet guy," Ms. Carter said. "All you saw of him from the beginning was the car would drive up, the garage door would open, the car goes in the garage and the door closes again. That's it." An older man she believed to be Mr. Baratov's father would drop by once a week to take out the garbage and do the general upkeep outside, Ms. Carter said. Mr. Baratov also had a bold presence on social media. On Facebook, Instagram and AskFM, he portrayed himself as a hard-working computer whiz and entrepreneur who was already a millionaire in his teens.

He boasted that getting suspended from high school in 2013 gave him the time to set up his own business. He completed school online, he said in one post. He said he was soon wealthy enough to buy a BMW and a house.

"Just using a few computer skills I've learned online," he wrote on his Instagram account next to photos of himself with fancy cars.

Mr. Baratov also had a girlfriend, who neighbours saw coming and going in the car with him. She would sometimes wait outside in the drive, but did not speak much to anyone.

Two or three times a year, Mr. Baratov held loud parties, including one at Halloween, that drew high-end cars and revellers into the early hours. Kids would flock to get their photos taken with the luxury vehicles, and neighbours grumbled about the loud music. Mr. Baratov's friends were described as close to him in age, with similar tastes.

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According to property records, Mr. Baratov bought the house in Ancaster in September, 2015, for $642,000. On Monday, Ms. Carter said, a for-sale sign appeared in front of the three-bedroom home. The asking price was $926,000, but the listing has been taken down. Mr. Baratov co-owns the property with a couple, 57-year-old Akhmet Tokbergenov and 47-year-old Dinara Tokbergenova. Their relationship to Mr. Baratov could not immediately be confirmed, but U.S. investigators have noted that Mr. Baratov used aliases that include Karim Akehmet Tokbergenov, and Kay and Karim Taloverov.

At the address believed to be his family's home, just a few minutes away by car, a man and a woman arrived in a white Mercedes SUV and drove into the garage, closing the door behind them without stopping to speak. A neighbour said the couple live there with a daughter.

Eric Goforth, a university student who lives in a neighbouring house, said on Wednesday when he heard about the cars connected to the arrest in Ancaster, he knew it could only be the man's son, whom he knew as Karim from his vanity licence plate. He described seeing a Lamborghini and an Aston Martin at various times. "I was blown away," Mr. Goforth said of his reaction to news of the arrest.

With a report from Rick Cash