Police said passers-by found a wallet with Lalonde's identification on the banks of the Ottawa River on Aug. 1 near the Bowater mill in Gatineau.
Police were later able to find a bone a few metres from the wallet that was a DNA match for Lalonde.
Lalonde was last seen leaving his home in Gatineau on Jan. 15, 2011 and was believed to have taken his bicycle to go fishing on the Ottawa River.
Police are still investigating Lalonde's death, but say they believe it was accidental.
Anyone with information on the circumstances of the death of Sébastien Lalonde is asked to contact Detective Sergeant Stephen Dumoulin at 819 243-2345 , ext 7647.