Hong Kong (CNN Business) The death of a Canadian entrepreneur has left a huge stash of cryptocurrencies locked off from the people who own them.

Quadriga, Canada's biggest cryptocurrency exchange, said it's unable to gain access to $145 million of bitcoin and other digital assets after Gerald Cotten, its 30-year old CEO and co-founder, died of complications arising from Crohn's Disease while traveling in India.

Many of the digital currencies held by Quadriga are stored offline in accounts known as "cold wallets," a way of protecting them from hackers. Cotten is the only person with access to the wallets, according to the company.

The unusual case highlights the risks investors face looking after their assets in the thinly regulated industry.

Cotten's death has plunged Quadriga into crisis and left it struggling to figure out how to refund more than 100,000 of its users.

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