Police officers on Sunday guarded the entries to the East Vancouver house where Adam Lo regularly parked a black Audi Q7, the luxury SUV he is accused of driving into a crowded festival street Saturday night, killing 11 and injuring more than two dozen others.

Mr. Lo has now been charged with eight counts of murder.

Police have given no immediate indication of what might have propelled Mr. Lo’s alleged involvement in the worst tragedy to strike this city in a generation and Mr. Lo said little about himself on social media.

But police, who said the 30-year-old man struggled with mental-health issues, were often seen at the house - including earlier this month, neighbours said. And posts made for online fundraising efforts suggest Mr. Lo lived in an environment that was itself beset by tragedy.

The family lives in Vancouver’s Victoria–Fraserview neighbourhood, on a quiet street in the city’s south-east populated by immigrants from greater China and the Philippines. It is located a seven-minute drive from the site of Saturday’s carnage, at a Filipino cultural festival.

The family — Mr. Lo, his brother Alexander and their parents — moved in more than a decade ago, said a close neighbour. Mr. Lo’s mother corresponded with neighbours in Chinese. A Facebook account that appears to belong to Mr. Lo says he is from Kaohsiung, Taiwan.

The father died of an illness not long after they arrived, the neighbour said.

Their mother, Lisa, is a “nice lady,” said another neighbour. She showed text messages with exchanges of new year’s best wishes. The Globe and Mail is not identifying the neighbours because they fear the consequences of being associated with the deadly events of this weekend.

But their home showed signs of trouble. Police were occasionally present, including earlier this month, the second neighbour said. Police came within the last two weeks to ask for security camera footage, the neighbour said.

The sound of yelling could sometimes be heard from the home, the first neighbour said. “He always was yelling with his mom,” the neighbour said. “I don’t know why.” The neighbour said the altercations were not violent but added that Mr. Lo often exhibited signs of anxiety.

“He is really nervous,” said the neighbour, who occasionally interacted with Mr. Lo. “Very — always scared of something happening that might hurt him.”

Acting Vancouver Police Chief Steve Rai has said his department can’t speak to the suspect’s motive, but told reporters he faced major mental-health challenges.

Acting Chief Rai described him as having “a significant history of interactions with police and health care professionals related to mental health.” The department did not confirm how many times they had been called to the house in recent years.

On Sunday afternoon, Mr. Lo remained in custody.

It is unclear what he did for work. The Facebook account says he attended the University of British Columbia’s business school.

His brother, Alexander, was killed last year. Mr. Lo launched a GoFundMe page after Alexander was found dead on Jan. 28, 2024, in a home two kilometres from where the family lived.

Police arrested Dwight William Kematch on the scene and charged him with second-degree murder but have provided few details about his death. Court records in the case are subject to a publication ban, but Mr. Kematch’s lawyer Jim Heller confirmed Sunday that his client is set to begin his trial this October.

Mr. Lo, in several posts to GoFundMe, described the loss of his brother as financially and emotionally shattering.

Soon after, his mother was taken into intensive care after attempting suicide, according to the GoFundMe posts and neighbours. The neighbours said she remained in hospital for weeks. The family was also left with the cost of a laneway home it had built, and now rents out. A notice of claim filed in provincial court lists a series of alleged defects for the $213,000 structure.

“My mother took out significant loans to build him a modest tiny home, an endeavour already marked by painful encounters with builders,” Mr. Lo wrote on GoFundMe.

“The realization that he’ll never return home pains both me and my financially strained mother, unable to afford proper funeral expenses. I hope he can find peace with a dignified farewell.”

On the Facebook page, a Jan. 30, 2024, post shows a man and a boy standing against a celestial cloudscape. It is captioned “My Father and Brother.”

On GoFundMe, a memorial picture shows a portrait of Alexander perched against a black copy of the Bible. Mr. Lo wrote that he would attempt to have his brother recognized by Cirque du Soleil, where Alexander had worked.

“Another thing I will strive to do for you is to ensure you are placed beside our late father,” Mr. Lo wrote. “This is something you would have wanted, as you often spoke of him.”

On Sunday, the family’s home stood still in the sunshine.

The windows were shuttered, with only security cameras visible — and a copy of Bible, propped against glass on the second floor. It appeared to be the same edition that was placed on display for Alexander’s memorial.