The death of a Waterloo man, found lying outside a school on Memorial Day morning, remains a mystery. Waterloo Police Lieutenant Michael McNamee says the state medical examiner was unable to determine exactly how 69-year-old Dennis Washburn died.

McNamee said at the time Washburn was found in the lawn of the former Longfellow Elementary School in Waterloo, it appeared he had been badly beaten. Washburn died 10 days later at a hospital.

Family members believe the veteran had likely been drinking at a bar and was beaten up and left for dead. McNamee said the case remains open, but investigators have exhausted all their leads. “Perhaps somebody from the public who hasn’t stepped forward will do so or I guess it’s still possible that some other evidence that we don’t have at this point becomes available to us,” McNamee said. “At this point, there’s not a whole lot left for us to do, other than keep it open and hope we can develop a different lead.”

The state medical examiner ruled the cause of Washburn’s death as “undetermined.”