A military source says Howard Richmond was questioned and detained Friday as police executed a search warrant on his home in Winchester, Ont., south of the capital.
The body of Richmond's wife, 28-year-old Melissa Kelly Richmond, was found in a small ravine near a shopping centre in suburban Ottawa earlier this week.
Although police have not released the cause of death, it has been reported that she was stabbed several times.
Richmond, a warrant officer who has completed three tours of Afghanistan, is scheduled to appear in court Saturday via video conference link.
Police have not released Richmond's name and haven't indicated if the suspect they have arrested will be charged with first or second degree murder.
Richmond reported his wife missing after she went for a late-night drive on July 24 and never returned.
Her vehicle, with the distinctive license plate RPGGIRL, was recovered two days later in the parking lot of a shopping centre.
Richmond, in an interview with CBC on Thursday, said he has received treatment for post-traumatic stress disorder and his wife of eight years was a "rock" through the entire ordeal.