Gatineau police said they were called to a building at 45 Symmes St. in their western Aylmer sector around 8:20 p.m.
On Monday morning they confirmed a 42-year-old woman was found dead at that building and the incident is considered suspicious.
A 49-year-old man who Gatineau police called an "important witness" has been arrested in connection with the death, police say.
The Gatineau police's major crimes unit continues to investigate and will meet with the man later on Monday, said spokesperson Pierre Lanthier in a news release.
Lanthier said the woman's family is still being contacted, so more details on who she is are being withheld.
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