For Tom Casey, the awful scene in Dallas this week was a familiar one: fellow police cut down by sniper fire or scrambling for cover.

This time, Casey watched it unfold on TV from his living room in Livingston Parish; 43 years ago, he saw it from a Marine transport helicopter over downtown New Orleans, where he spent hours exchanging gunfire with a sniper atop the Howard Johnson hotel on Loyola Avenue.

“You see an officer bleed to death, it hurts,” said Casey, now 74 and retired from the New Orleans Police Department. “I never met any Dallas cops, but I felt like they were my brothers. And I felt the same watching that on TV as I did in that helicopter.”

If this week was a reminder of how divided America remains over the issues of race and policing, the eerie parallels between the sniper shootings in Dallas on Thursday and those in New Orleans in January 1973 made a case for how little things seem to have changed over the past four decades.

Then, as now, the shooter was a black military veteran who targeted white police officers, seeking retribution for perceived police brutality against blacks. And both sides of a simmering debate over race and justice looked on aghast at violence that most — no matter what their views — could not condone or even fathom.

“I am just sad we seem to be trapped in this evil loop — it’s a sad, sick ‘Groundhog Day,’ ” said Bruce Nolan, who covered the culmination of Mark Essex’s attack on New Orleans as a rookie reporter for The Times-Picayune. “I can’t believe we are so broken that we have to go through this again.”

After growing up in Emporia, Kansas, Essex was angry about prejudice he experienced as a Navy sailor before he was discharged because of behavior and character problems. He aligned himself with the Black Panthers radical group in New York in the early 1970s and then moved to New Orleans to join a friend and train in vending machine repair.

Had Essex linked up with the Black Panthers in New Orleans, he would have landed on the city police force’s radar. But he didn’t, said Larry Preston Williams Sr., who at the time had helped infiltrate numerous white and black extremist groups in New Orleans as a member of the Police Department’s Intelligence Division.

“As far as black extremists, his name never came up,” Williams said. “Because Mark (in New Orleans) was what you call today a lone wolf, and you never know about them until they do something very high-profile or public.”

Essex would soon do just that. He began about six weeks after police came out in force in response to demonstrations and class boycotts at Southern University in Baton Rouge on Nov. 16, 1972, a clash that left black students Denver Smith and Leonard Brown dead from shotgun wounds less than nine miles from where black man Alton Sterling was killed by two white Baton Rouge cops early Tuesday.

On New Year’s Eve 1972, Essex made his way to New Orleans’ Central Lockup and shot police cadet Alfred Harrell Jr. with a .44-caliber Magnum carbine. He then tripped a burglar alarm at a nearby warehouse and shot officer Edwin Hosli Sr., who arrived to investigate the alarm. Harrell, Essex’s only black victim, died immediately. Hosli, who was white, died two months later.

Essex evaded capture for a week, but he came out of hiding on the morning of Jan. 7, 1973, a Sunday, when he used his carbine to wound a grocer he feared was aiding the police.

He then stole a car at gunpoint, drove to the Howard Johnson’s in the 300 block of Loyola Avenue and killed the hotel’s general manager; its assistant manager; and two guests, a husband and wife who had been married for seven months.

Authorities rushed to the site as they were inundated with reports of shots ringing out from various places in the 17-story hotel, across the street from City Hall and state offices. Essex was eventually cornered on the rooftop, but police were unable for hours to get to him and stop him.

NOPD officers Phil Coleman, Paul Persigo and Deputy Superintendent Louis Sirgo all died trying. About a dozen other people were wounded, including an officer whose injury Williams tended to while they were under a tree in nearby Duncan Plaza.

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Casey, then assigned to the NOPD’s now-disbanded Felony Action Squad, was spending the day in Mississippi getting a carpet installed in the back of his new Dodge van when he noticed people at the shop fixated on a TV set. He remembers someone screaming, “There’s a sniper on the roof of the Howard Johnson’s in New Orleans, and they’re killing cops!”

Casey immediately hopped into his van and began heading back to his home in Metairie. He had been warned not to drive the bulky van faster than 60 mph, but the speedometer needle was on 95 the entire way.

When he got home, he grabbed his rifle and ammunition. He slipped into a powder-blue police shirt — leaving his jeans on to save time — and said goodbye to his wife, who begged him to stay off-duty.

But that was no option, Casey said. For one thing, when Casey was working undercover and couldn’t pick up his paycheck as normal, Sirgo would personally deliver it to the officer’s wife to make sure the couple could pay their bills.

“It was like if somebody came in your house and killed your wife, you know?” Casey said about joining the many colleagues who had braved Essex’s gunfire and trapped him on the roof. “It’s family. You’ve got to fight and prevent someone else from being killed.”

Casey arrived to a chaotic scene. What perhaps best illustrates how much Essex’s attack initially overwhelmed authorities is the fact they had set up their command post in the Howard Johnson’s lobby.

That meant top city officials — including Police Chief Clarence Giarrusso and Mayor Moon Landrieu, the father of current Mayor Mitch Landrieu — and their subordinates had to navigate the danger outside to access the post.

The tide turned when a Marine transport helicopter crew from Belle Chasse arrived and offered to fly officers over the hotel roof so they could fire down on Essex.

Casey and a group of fellow officers volunteered to board the chopper, piloted by Charles H. “Chuck” Pitman, who later retired as a lieutenant general in the Marines.

Essex was hiding in a concrete cubicle on the roof but occasionally ventured out to fire at the chopper as it made a number of passes over him. Pitman, Casey and their companions couldn’t immediately get a clear shot but kept flying over the hotel.

Then, about 9 p.m., some 10 hours after the hotel came under siege, the chopper caught Essex too far away from his cubicle. Casey, the others who had rifles in the helicopter and officers stationed in surrounding buildings emptied their weapons. Essex collapsed and died, ultimately being struck more than 200 times after killing nine people and wounding 13 others during his two-day spree.

It would be many more hours, however, before authorities were certain he was dead and there were no other snipers on the loose.

This week, Dallas authorities used more advanced tactics to stop the sniper they encountered, killing him with a robot-delivered bomb.

But like their New Orleans counterparts, officers this week demonstrated the willingness to risk their lives for their city and their comrades.

“After all these years, the same things keep happening, both for good and for ill,” Nolan said. “There were heroes that day, and there were heroes (this week). There was evil that day, and there was evil (this week).”

Follow Ramon Antonio Vargas on Twitter, @RVargasAdvocate.