Richard E. Joyal, 62, was gunned down on Thursday, just after he had withdrawn money from a bank in Port-au-Prince, the Caribbean nation's capital city.
Police spokesman Frantz Lerebours told The Associated Press on Monday night that he couldn't provide more details on the arrest.
Police have said Joyal was shot three times by a passenger on a motorcycle. The two people on the motorcyle then sped off with the man's bag.
Joyal had just withdrawn $1,000 at the bank, but authorities say they found the cash in his wallet.
Joyal was originally from Winnipeg but had lived in Quebec City for the past two years. He was with an order of Catholic brothers, the Marianists.
Joyal was on a temporary mission in Haiti and was scheduled to return this week.
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