Top Huawei executive Meng Wanzhou has been sent bullets in the mail while under house arrest in Vancouver, according to court testimony.
It was one of several alleged death threats revealed on Wednesday by the company providing her security.
Ms Meng was detained in 2018 on charges relating to allegedly misleading HSBC about Huawei's dealings in Iran.
Her case has created a rift between China and Canada, with Beijing repeatedly calling for her release.
The chief financial officer of Huawei was arrested at Vancouver International Airport on a warrant from the US, where she is facing charges of bank fraud and potentially causing HSBC to break US sanctions.
Days after she was released on bail, she was placed under house arrest in Vancouver. She has been fighting against her extradition to the US, which wants her to stand trial.
The threats were revealed at the British Columbia Supreme Court by Doug Maynard, chief operating officer of security firm Lions Gate Risk Management.
He said Ms Meng received "five or six" threatening letters at her residence in June and July 2020 and that the letters were "easily identifiable by markings on the outside". He added that "sometimes there were bullets inside the envelopes".
The role of the Vancouver police and any investigations is unclear.
Ms Meng has been in court pushing for conditions of her bail to be loosened, including dropping the daytime security detail that constantly follows her.
She is permitted to leave home between 6am and 11pm and pays for a round-the-clock security detail. She also wears a GPS tracking anklet as stipulated by her bail conditions.
The government has also granted family members of Ms Meng permission to travel to Canada, sparking controversy.
Conservative MP Raquel Dancho said the exception was an "insult to the millions of Canadians who were told by this government not to visit loved ones" over the holidays.
She called the move disappointing, noting that Beijing detained two Canadians soon after Ms Meng's arrest in December 2018 and has held them in prison ever since, subjecting them to interrogations.
Ms Meng's defence lawyer has argued that Canada is effectively being asked "to enforce US sanctions".
Huawei has been one of the main targets of the Trump administration's attack on Chinese companies that it deems are security threats and pass data to the government.
The US has placed harsh restrictions on Huawei and has banned its 5G equipment from its networks. It also added 38 names linked to Huawei to a trade blacklist.
This week Huawei came under fire for technology that identifies people who appear to be of Uighur origin among images of pedestrians.
Huawei had previously said none of its technology was designed to identify ethnic groups.