A passerby found the woman washed up on the river bank on Friday evening.
Mélançon and Marcel Pronovost were last seen May 11. Pronovost's body was recovered in the couple's car four days later, in the river across from their home.
A coroner will conduct an autopsy to confirm the identity of the body pulled from the river, as well as try to determine the cause of death.
There is so far no known motive or reason why the couple would have driven their car into the river.