Christine Villines waited for an officer for more than 31/2 hours after another motorist sideswiped her truck near City Park last month and then hit several other vehicles before driving off. She finally gave up. If she hadn’t called the police back the next day, she said, the wreck might never have been recorded as a hit-and-run.

With average police response times tripling since 2010, reporting crimes in New Orleans is increasingly an act of persistence. Officers often arrive at scenes hours late to find victims long gone and, in many instances, then mark the crimes “unfounded” — meaning that in the department’s view, they never occurred at all.

The increasing number of “unfounded” incidents is almost certainly deflating official crime statistics and making the city appear safer than it really is, according to a joint investigation by The New Orleans Advocate and WWL-TV.

Since 2010, the percentage of all incidents handled by the New Orleans Police Department that are marked unfounded has jumped from 10.4 percent to more than 17.9 percent, according to department records.

If police wrote reports after they answered 911 calls at the same rate as they did in 2010, an additional 1,332 major crimes — including aggravated batteries, burglaries, robberies and thefts — would have been reported through mid-August of this year. Were all those crimes counted, the crime rate so far this year would be 12 percent higher than what’s been reported.

It’s impossible to say exactly how many of the calls the NOPD deemed unfounded did not, in fact, stem from actual crimes. At least some proportion of 911 calls turn out to be made in error each year.

But it’s clear that the increasingly long waits for an NOPD response are having an effect.

Between 2010 and 2012, the rate of unfounded crimes hovered around 10 percent. As response times began to rise the next year, so did the percentage of unfounded cases.

The data show a clear correlation between the length of time it takes for a squad car to arrive on the scene and the likelihood that the call will be deemed unfounded.

Less than 15 percent of the calls that police responded to in six minutes or less so far this year have been classified as unfounded or “gone on arrival” — another designation that doesn’t get counted in overall crime numbers and that generally gets little follow-up. But that proportion shoots up to more than 38 percent for calls in which police took more than 90 minutes to arrive.

Overall, the number of calls marked up as unfounded or gone on arrival has shot up from 15 percent in 2010 to 24 percent of calls this year.

Concerns about crime “downgrading” — reducing crime numbers on paper but not in reality, often for political reasons — are nothing new. A 2013 Louisiana legislative audit concluded that roughly a third of the serious crimes the office examined should have been reported to the FBI as major crimes but were not.

There’s no evidence that the crimes lost to the “unfounded” category in New Orleans have their foundation in political spin — rather, it appears skyrocketing response times simply mean police aren’t able to interview witnesses in many cases.

Inspector General Ed Quatrevaux, who also has issued reports critical of NOPD crime data, said he believes all those “unfounded” calls are almost certainly having an impact on the major crimes the department reports to the FBI.

“We are properly and professionally skeptical of the quality of the data,” Quatrevaux said. “How many crimes do we actually have? Of what variety?”

NOPD Superintendent Michael Harrison acknowledged in an interview last month that with response times spiraling, far too many calls are being marked as unfounded. He said the department will retrain officers to ensure that when victims are gone, officers call back the initial 911 complainant’s number.

“That’s a major training issue that we’re dealing with because ‘unfounded’ means the crime did not happen,” Harrison said.

Last week, as The New Orleans Advocate and WWL-TV reported on rising response times, the department made a significant policy change. Cops must now have a supervisor’s approval before labeling a crime “unfounded.” If the person who reported the crime has left, officers are supposed to mark the call “gone on arrival” and then give the complainant a call.

“It means the citizen was gone when we arrived,” Harrison said. “It doesn’t mean the crime didn’t happen. It just means they weren’t there.”

The NOPD is also tasking its new Alternative Police Response Unit, desk-bound officers who take reports over the phone to reduce the backlog for officers in the field, to follow up on cases marked as unfounded or gone on arrival, spokesman Tyler Gamble said.

Whether the policy shift will have a meaningful effect is unclear. The civilians who have given up waiting on police officers to appear in person may ignore the sergeants and lieutenants stuck calling them back later on.

Capt. Mike Glasser, president of the Police Association of New Orleans, predicts the new rules simply will add one more task to overburdened supervisors’ to-do list.

“I don’t see where this makes a difference. We’re still marking it up, and we’re still not doing anything with it because the people are gone,” Glasser said. “The answer is to send cops sooner, not send more cops when there’s no one there.”

A veteran patrolman who spoke on the condition of anonymity because NOPD officers are not authorized to speak to the media said the increasing number of “unfounded” incidents is a direct product of rising workloads.

“You never do (catch up). A lot of times, how they’re catching up now, the rank has to do callbacks on any call holding more than an hour. ... They might call back two times and then mark it up ‘unfounded,’ ” the officer said. “A lot of times, people need the police, but they went to go get groceries, go get their kids. (We) mark it up unfounded to clear up the backlog. These are people that still need police help.”

Incidents uncovered by The New Orleans Advocate and WWL-TV show that even serious crimes are sometimes marked as unfounded. Police wrote up a report on an attack on a man in the Marigny last month only after his friends went to the media. A woman left unconscious by an unknown assailant in the French Quarter this year said she had to go to a police station multiple times before an officer would write up a report. A Gentilly woman claimed she had to call 911 “hundreds” of times to get a police report on a domestic battery.

More than 36 percent of this year’s calls reporting aggravated batteries and assaults — attacks or threats with weapons — were dismissed as unfounded, compared with about 27 percent in 2010. Nearly 20 percent of robberies were marked unfounded this year, 4.4 percentage points higher than in 2010.

Even minor crimes that go unacknowledged can get worse without a police response.

Brock LaBorde’s theater on St. Claude Avenue, the New Movement, was burgled three times during one week in August. The first time, police were so tardy that nobody was around to tell them what happened.

“They showed up at 3 (a.m.), and no one was here. Of course, no one was here. And then they just left, saying it was an unsubstantiated call,” LaBorde said.

The same club was robbed again two days later. (It also was robbed a third time that week, after police took a report).

The proportion of burglaries that go unrecorded has increased by more than half in the past five years, jumping from 15 percent to 23 percent.

Harrison said that in the future, calls like LaBorde’s should never just be filed as unfounded.

“Those are tweaks we obviously need to make to make sure we’re capturing all the data, we’re communicating with all the citizens, all the businesses, all the visitors, to make sure that if something happens, we know about it, and if we can’t get to it right there, we can explain why and make other plans,” he said.

Minor crimes that go unacknowledged also can leave civilians feeling discouraged.

Villines said she had been meaning to replace her beat-up 1990 Ford Ranger even before it was damaged in the hit-and-run near City Park. But she felt strongly that the incident deserved a police report.

The officers who finally did take the report, she said, were “really nice and apologetic.” They explained to her that “if the perpetrators left, we don’t make it a priority.”

Villines also recalled the conversation she had with an insurance company representative when she said police never arrived the day of the incident.

“You can’t explain it to people who don’t live here,” she said. “You just can’t get a cop sometimes.”

MORE RESPONSE TIME COVERAGE

Slower, 'unacceptable' New Orleans police response times have become norm; see average wait times by area

In crime-ridden New Orleans East, police response times almost twice as long

Harrowing stories surface amid rising New Orleans police response times

911 operator who never told cops about threats to murdered woman resigned under investigation

City Council members grill police chief about slow response times

NOPD chat replay: Who's to blame for skyrocketing response times? What can be done to fix issues?

Interactive maps: See New Orleans police response times in your neighborhood

Analyzing increasing police response to major New Orleans crimes

Staff writer John Simerman contributed to this report.