Lindsay Clarke Prior, known as Bert, went missing at the end of January.
Despite extensive searches by friends and family, no trace of Bert was found.
But in March police were alerted to a body which had been found in the River Nene which they believed to be Bert.
Now his family has revealed on social media that testing has confirmed the identity of the body.
A statement said: “Thursday morning came the news that we expecting, but never wanted to hear.
“Northants Police have confirmed by dental records that the body recovered almost two weeks ago was that of Bert.
“The family are devastated to hear this sad news.
“It has been a long 11 weeks, but having everyone’s support had helped us through.”
More than 200 people had expressed their condolences to the family on Facebook last night.