Susan Ledyard's family and friends gathered at the Brandywine Brewing Company in Greenville, Delaware.
On July 23, her body was pulled from the river and her car was found miles away.
At first, her family believed her death was a tragic accident, but they say police recently told them they were looking into her death as a possible homicide.
"Someone out there is responsible for her death. Someone out there is waking up every day and going to sleep every night knowing that they have taken her life and shattered her family," said Susan's sister, Meg Morrissey-Heinicke.
Her loved ones have been putting up posters in the area, begging people to come forward with information.