Mayor Mitch Landrieu called Ronal Serpas his most important hire.

The new mayor marked the occasion in May 2010 with a news conference at Gallier Hall, heralding the return of a home-bred cop with a penchant for reform who would reshape a New Orleans police force tattered by scandal and a history of appalling misconduct and bracing for federal intervention.

The honeymoon was short-lived, if it happened at all.

Serpas weathered criticism almost from the start, much of it from within as the new New Orleans Police Department superintendent set about on a course of stiff discipline for officer misconduct large and small. Serpas fired scores of cops and kicked a cadre of captains and other rank to the curb while elevating others — including his eventual replacement, Lt. Michael Harrison — to a tier of new command posts he created.

Four years later, the data-driven police chief in a city plagued by violent street crime, leading a force beset by steeply dwindling ranks, said he was through.

Serpas announced his retirement from the department “and from public service” at a Monday news conference at City Hall.

He stood alongside Landrieu, a second-term mayor who appeared to have grown distant from, if not disenchanted with, his early choice to lead the NOPD into the future. Whether Serpas’ sudden departure — his final day was Monday — came on the business end of a mayoral ultimatum, a shove or even a suggestive nudge was not immediately clear. But it appeared to have been months in the planning.

At the news conference Monday, Serpas, 54, touted support from the mayor, “who I’ve enjoyed working with every single day.”

He alluded to a new job he’d lined up that will let him stay in New Orleans. Loyola University, where Serpas has taught classes in the past, announced later Monday that Serpas will join its criminal justice program, in what sources say is a plum, tenured post.

Landrieu offered praise for Serpas, who left the top police post in Nashville, Tennessee, to return to New Orleans, where he had quickly risen to second-in-command under then-Superintendent Richard Pennington in the mid-1990s.

“It is with regret that we see you retire today,” Landrieu said.

He added that “given where the chief is in his life and what his dreams are for his future and where the city is, this actually falls beautifully into the strategy to begin to develop the city for a new generation of leadership.”

That new generation starts with Harrison, a 45-year-old New Orleans native whom Landrieu tapped for the “interim” superintendent role. Harrison, who since 2012 has commanded the 7th District — covering most of New Orleans East — was sworn in immediately after the news conference by Landrieu. Serpas pinned the superintendent’s badge on Harrison, who described his former boss as “a coach, a teacher, a mentor, a friend.”

While officials sought to portray the changing of the guard Monday in purely positive terms, rumors of Serpas’ departure have been circulating for months, and some observers pointed to a relationship with Landrieu that had become strained.

During a heated re-election campaign this year in which his opponents called vehemently for Serpas’ head, Landrieu offered tepid support rather than a vigorous defense of his police chief.

In June, during a nearly two-hour interview with The New Orleans Advocate, Landrieu pontificated over a number of pressing issues, but when asked if he had confidence in Serpas, the mayor offered a simple, “Yes.”

Next question.

“It seems as though there’s been a fairly chilly relationship with City Hall for a little while now. It seems like it’s been since last year,” said Donovan Livaccari, an attorney and spokesman for the local Fraternal Order of Police lodge.

Tulane University criminologist Peter Scharf said there seemed to be an “odd relationship” between Serpas and the mayor, as well as a deepening rift.

“A lot of police officers were mad at Ronnie for this or that, but if you really look closely, there was some responsibility on the mayor as well,” he said.

Serpas’ defenders say the deck was heavily stacked against him.

As reform-minded as Serpas may have been, a federal consent decree that Landrieu and U.S. Attorney General Eric Holder signed in July 2012 laid out a wide-ranging blueprint for changes at the NOPD that took the bat out of Serpas’ hands, Livaccari said.

“Being a reform chief was kind of his thing. He liked to always say he was an agent of change,” said Livaccari, a frequent critic of Serpas and the administration. “He wasn’t able to implement any change because all the changes were forced upon him from outside forces. He never had the opportunity to achieve his goals.”

In the meantime, Serpas has been quick to note that he never had a chance to hire a new corps of officers to replace the hundreds who have retired or resigned or been fired under his watch due to a hiring freeze put in place by a Landrieu administration looking to fill a gaping, $100 million budget deficit.

In some eyes, Serpas became the fall guy for the manpower shortage, the resulting complaints over delayed police response times and, among officers and some customers, controversial city regulation of the off-duty police detail system that the federal consent decree mandated.

Changing a troubled police culture without the ability to hire made for a tall order, said Michael Cowan, of the New Orleans Crime Coalition, a staunch Serpas supporter.

“It’s fresh blood and it’s changing the mindset of the people who are there. That’s a very heavy lift,” Cowan said. “Anybody who thinks managing a modern urban police department is anything but a hell of a challenge doesn’t know what they’re talking about.”

Serpas, who left with a $186,000 salary, will make $157,000 a year in pension benefits, or about $13,000 per month, according to the city. Harrison’s salary jumps from $78,000 to $150,000.

Controversy surrounded Serpas from the beginning, with questions swirling first about whether he had an inside track in the national search for a superintendent and then about whether he had backdated a sworn document to meet a deadline for picking up retirement benefits. The critics have never fully quieted down, with Serpas taking steady heat for everything from a perceived lack of progress in reducing violent crime — and questions over proper recording of crimes — to the NOPD’s sometimes aggressive tactics.

Over the course of one week in 2012, police shot and killed two young African-American men, one during a traffic stop and the other during a drug raid. The latter shooting, which claimed the life of Wendell Allen, 20, eventually prompted charges against Officer Joshua Colclough, who is serving a four-year prison term after pleading guilty to manslaughter.

The incidents prompted renewed calls for Serpas to step down, calls that were especially loud in the black community.

Serpas faced some of his harshest criticism in 2011, when it emerged that Police Cmdr. Edwin Hosli — one of Serpas’ closest friends on the force, who had the prestigious position of overseeing the French Quarter-based 8th District — had set up a limited liability company for a side gig in which he and other officers were paid extra by the city to review traffic-camera tickets. The practice violated NOPD policy, and the news of the arrangement broke as Serpas was starting to embark on a controversial overhaul of private detail work.

Amid the controversy, Landrieu himself stepped in and suspended Hosli, a rare instance in which the mayor seemed to undercut the chief’s authority.

The Hosli matter raised questions about internal politics in a department that has long been factionalized. While Serpas has at times been an unsparing disciplinarian — touting a “you lie, you die” policy over police misconduct — there was no rush to judgment in the Hosli case. Though Hosli was removed from his 8th District command, he was eventually restored to a leadership post, and he retired from the force in June for a high-ranking job with the Sheriff’s Office.

His treatment differed starkly from that afforded to a group of seven captains and a major who fell out of favor with Serpas and were assigned to a newly created “Administrative Support Unit” based in a Federal Emergency Management Agency trailer in City Park. That group just won a ruling from the Civil Service Commission saying that the menial work the department has given them is essentially beneath them.

The most recent controversy came last week over the department’s failure to reveal details of an officer-involved shooting. Serpas said he had approved a press release over the incident, but it never went out.

There was no indication Monday that the snafu had anything to do with Serpas’ hastily announced departure.

But just last week, City Councilman-at-Large Jason Williams suggested on “Happy Hour,” a little-noticed podcast that airs online on, that at least five members of the council were prepared to terminate Serpas — a power bestowed on the council by the city charter but never before exercised.

If the threat was real, some council members claimed they were unaware of it.

“That’s news to me. No one consulted me on it,” District E Councilman James Gray said. “I would not have (voted to remove Serpas). I would tend to let the mayor make his selection.”

Gray said Serpas “served in a very tough time,” amid the onset of federally imposed reforms to the force and a loss of roughly 400 officers, leading to woefully undermanned district stations.

“I often wondered why Serpas and the mayor didn’t use that as an excuse more often,” Gray said.

But Williams called Serpas’ departure “the right move for our police force and our city,” citing low officer morale amid a recruiting drive that so far has not done much to restore the depleted ranks.

In a written statement, Williams referenced Serpas’ famously data-driven approach to the job.

“When it comes to crime, it isn’t just about statistics, it is about people feeling safe in their homes and throughout the city,” Williams said. “Changing the leadership of our police force is a step in the right direction.”

Landrieu suggested the job will be Harrison’s to lose.

“I would say that possession is nine-tenths of the law,” Landrieu said of Harrison’s chances to lose the “interim” tag.

But this honeymoon also may be short-lived.

Already, Harrison’s ascension to the top spot in the department has drawn catcalls from some circles, with questions over his qualifications for the job.

The court-appointed monitoring firm overseeing the NOPD reforms is expected to issue its next progress report next month. Its last report chided the department for doing a poor job redrafting policies and tracking several areas of mandated changes.

Whether Landrieu’s administration will seek any delays in implementing the reforms on account of Serpas’ departure is uncertain. Either way, the challenges remain.

“The passing of the guard doesn’t mean the problems that have beset the Police Department are fixed,” said Metropolitan Crime Commission President Rafael Goyeneche. “It just means there will be someone else responsible for moving the department forward.”

Follow John Simerman on Twitter, @johnsimerman.