Oliwier was last seen near the riverbank at The Flood Road bridge in Gainsborough late on Monday, May 22.
A spokesman from Lincolnshire Police said: “You will be aware that we have had a significant search effort around the River Trent in Gainsborough as we try to locate Oliwier.
“Today (Friday, May 26) that has included a specially-trained underwater search team and officers searching the banks.
“We are saddened to report that this afternoon, we have recovered a body around 200m from the Flood Road bridge.
“Officers remain on scene as we start the difficult process of removing the body, and we ask that people do not share images or posts from the location.
“No formal identification has yet been carried out, so we are unable to confirm that it is Oliwier at this time. Procedures to identify the body are on-going.
“Oliwier’s family have been informed of developments and our thoughts are with them at this most difficult of times. We ask that their privacy is respected.
“We are currently treating the death as unexplained, and we are liaising with the Coroner.”