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Nigel Wright, former chief of staff to Stephen Harper, took a leave of absence from Onex to join Mr. Harper’s team early in 2011 and became a key player in the Conservative government.Justin Tang/The Canadian Press

Nigel Wright, a long-time Onex executive and former chief of staff to Conservative Prime Minister Stephen Harper, has died.

Onex Corporation announced his death in a statement Tuesday.

Mr. Wright joined the investment firm in 1997.

He then took a leave of absence to join Mr. Harper’s team early in 2011 and became a key player in the Conservative government.

But he resigned in 2013 in the midst of the Senate expenses scandal.

He subsequently returned to Onex, moving to the United Kingdom to join the firm’s operations there.

Company President Bobby Le Blanc called Mr. Wright a consummate gentleman who set the standard for professionalism.

“Over nearly three decades with Onex, he was committed to its values, its culture, and most of all its people, who regarded him with deep admiration and affection,” Mr. Le Blanc said in a statement.

The company did not provide a cause of death.

Former colleagues from politics also remembered him fondly.

“Very saddened to hear of the passing of Nigel Wright,” wrote Ian Brodie, another of Mr. Harper’s former chiefs on social media.

“In addition to his business and investment acumen, Nigel had a long life of public service and I remember all my times working with him with great fondness. My sympathies to all his friends and family.”