Gail and Paul Casey are the parents of Army Sgt. Patrick “Pat” Casey, who was killed in the District in September 2011.

No parent should have to be responsible for doing the investigation into their child’s death, but that’s exactly what we had to do when the D.C. police and the U.S. attorney’s office for the District of Columbia willfully failed to complete a thorough investigation after our son was killed in our nation’s capital.

His death, and the resulting “investigation,” is a national tragedy that remains shrouded in secrecy and deceit by those same institutions. He fought for his country, but only we would fight for him.

Our son, Army Sgt. Patrick “Pat” Casey, led troops in combat in Afghanistan. After serving, he returned home to study international affairs at George Washington University, only to have his life cut short by a violent criminal offense. On Sept. 23, 2011, Pat was at a downtown McDonald’s when three barhopping, belligerent and aggressive strangers from Virginia initiated a verbal exchange that escalated to pushing and spilled outside. One of the trio sucker-punched Pat from behind. He fell, striking his head on the sidewalk. Four days later, Pat died.

The U.S. attorney’s office and the police rushed to judgment based upon biased and factually incorrect information proffered by the perpetrator’s lawyer on Sept. 29. The very next day, police officials held a news conference that forever poisoned the investigation. They falsely claimed the trio had been interviewed and publicly declared that Pat was to blame for his own death. The police statements were contradicted by evidence in the police files or easily available, including a security video that, had it been properly and timely reviewed, would have illuminated critical events. Also, an eyewitness said that the three men were “drunk and out of control” and that they, not Pat, started the altercation and that one of them threw the ultimately fatal punch before the three immediately fled.

With the assistance of a former federal prosecutor, we performed an exhaustive investigation that included obtaining — through the Freedom of Information Act (our initial requests were denied) — all the police files and the homicide standard operating procedures, and depositions taken in civil suits. It was clear the official investigation was not merely negligent and woefully inadequate, but crossed the line to serious and pervasive misconduct.

Even today, despite our relentless presentation of voluminous undiscovered evidence surrounding the attack (evidence that was always available had investigators searched for it), and documentation of multiple instances of negligence, incompetence and misconduct, the U.S. attorney’s office, headed by Ronald C. Machen Jr. and later Jessie K. Liu, and the D.C. police, headed by Cathy L. Lanier and now Peter Newsham, have rejected transparency and accountability. Instead, at every opportunity, they have endeavored to maintain the public’s trust by falsely claiming that their investigation was exhaustive and cooperative. This simply and demonstrably is not true.

Merely days after the attack, rather than first performing a thorough investigation, prosecutors offered the perpetrator a “queen for a day” immunity protection. According to police files, after a debriefing on Oct. 14, we were told the prosecutors “adopted [the perpetrator’s] version as fact.” Rejecting this version, the police submitted a warrant for second-degree murder on Oct. 20. The U.S. attorney’s office declined the warrant, and the investigation stopped.

Disgracefully, on Nov. 29, the same prosecutors and police officials responsible for the news conference together filed a “declination to prosecute” letter explicitly concluding, contrary to facts, that Pat’s death was justifiable as “defense of another.” This permitted the police (who had sought a warrant for murder) to close the case as solved, we were told, for statistical reporting. Credible investigations do not file false reports.

In December 2016, through our persistence in revealing and proving the facts, prosecutors finally withdrew the “defense of another” conclusion. In fact, a D.C. police report in February 2017, utilizing our findings, concluded that “a criminal offense occurred” and stated that based upon witness testimony “the punch that hit Casey was only believed to be ‘in defense of another’ by [the perpetrator] and by no one else.” Nevertheless, the prosecutors rejected police requests for subpoenas to gather more evidence and the D.C. police silently abandoned their responsibilities again.

Law enforcement officials sworn to serve and protect intentionally sacrificed the search for the truth and Pat’s reputation to cover up their failed investigation.

Our findings, supported by the D.C. police’s own February 2017 report, are not the grasping of grieving parents; everything is proven by documented evidence.

Commenting on another case in which a young man died and the police tragically failed in their responsibilities, Mayor Muriel E. Bowser (D) said “when something bad happens, we keep the public’s trust by looking into what went wrong and taking steps to make things right.” We agree. The police investigation warrants a competent, independent and transparent review.

The public’s trust and Pat’s legacy demand the truth finally be told.

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