The parents of a former graduate student and Army veteran who died after an altercation at a D.C. McDonald’s in 2011 want to clear his name.

Patrick Casey, who was 33 at the time of his death, sustained serious brain injuries after hitting his head on the sidewalk during a fight and died four days later. The U.S. Attorney’s office did not charge anyone for Casey’s death, ruling it a “justifiable homicide” after determining that the man who punched him to the ground — Jason Ward — was acting in defense of a friend.

Now almost five years to the day after Patrick Casey lost his life, his parents — Gail and Paul Casey — hope that D.C. authorities will reclassify his death. They have spent the past five years collecting evidence from the incident, which they believe demonstrates their son’s innocence.

The couple said the case should be reclassified as closed, due to insufficient evidence, or as suspended, based on the new evidence, Paul Casey said. They plan to present the new evidence to the U.S. Attorney’s office.

“We don’t think the truth has been told,” Paul Casey said. “Unfortunately our son’s reputation was unfairly tarnished.”

If the U.S. Attorney maintains the classification, the couple said they want to see the evidence showing that their son attacked the other man.

“We think we are entitled to know how our son died,” Gail Casey said.

The Caseys reviewed the McDonald’s security footage from the night of the altercation and filed a Freedom of Information Act request to obtain police documents from the case, including interviews with witnesses. The couple was able to compare the interviews to the surveillance video, which did not match up, they said.

They also received sworn testimonies from two civil lawsuits they filed last year against McDonald’s and the two men involved, Ward and Brian Giblin, as further evidence. The civil case with McDonald’s is still ongoing, but the couple settled their lawsuit with the men out of court, the Caseys said.

The couple contacted Matt Ornstein, a lawyer at the victims rights legal services organization Network for Victim Recovery, to help have their son’s death reclassified. Ornstein said the new evidence is compelling because the sworn testimonies from the other victims do not match what Ward recalled from the night.

“We’re not entirely sure what they looked at or how well they looked at it,” Ornstein said about the U.S. Attorney’s findings.

The new evidence shows that the men in the McDonald’s “spilled out” onto the sidewalk and that the man who Ward said he was defending was about six feet away from Patrick Casey when Ward punched Patrick Casey, Ornstein said. He said the distance was too far for Ward reasonably to have thought he needed to defend the other man.

Ornstein’s organization has not dealt with similar cases before, and he said he is not sure how long it would take to have the death reclassified.

Michael Koenig, a lawyer who worked with the Caseys as they collected evidence, said based on the evidence and his experience, the classification of the case “clearly needs to be changed.”

“They have done as thorough an investigation as any police officer or FBI agent I’ve ever seen in my 24 years of experience,” he said.