MEXICO CITY -- Jorge Zárate Medina and his wife, Ana Vanessa Vázquez, trotted into the Estadio Olímpico Universitario after passing the cheering onlookers spurring the 2017 Mexico City marathon runners on. Husband and wife crossed the finish line together, sporting identical times, in 3 hours, 24 minutes, 25 seconds. So impressive, Vázquez even qualified to the 2018 Boston Marathon.

There was one problem. Zárate and Vázquez hadn’t run the whole race. Far from it.

Along the marathon course, electronic checkpoints were set up at every five kilometers. As runners passed these markers, a chip in the official shirt handed to runners before the race logged their splits and automatically posted it to the official Mexico City marathon app.

Zárate and Vázquez didn’t log seven checkpoints, between the 5K and the 30K markers. They reappeared at the 35K mark with matching times of 2:34:34 -- a pace of 4 minutes, 25 seconds per kilometer. By comparison, the winner of the female division of the race, Peru’s Gladys Tejeda, maintained a pace of 3 minutes, 42 seconds per kilometer.

“We lived the Mexico City marathon to its fullest! Let’s go, Oaxaca!” Vázquez exclaimed on a Facebook post, since deleted.

The couple, who had posted training pictures on Facebook prior to the race, was disqualified from the race when official results were announced on Sept. 12, a little more than two weeks after the marathon. In all, 5,806 runners -- one in every five who began the race -- were deemed ineligible. “All of the people who were disqualified from the race were found to have crossed the finish line in a fraudulent manner,” said Javier Carvallo, the race director for the Mexico City marathon. “Most cases, we found, was course-cutting via the skipping of checkpoints.”

Zárate, who is running for Mexico’s Congress in the upcoming July elections, was singled out by media outlets in the aftermath of the race, just one of several incidents exposed in the days following the competition.

Zárate did not respond to repeated requests for comment by ESPN.

“You have [cheating] in marathons around the world,” Carvallo said. “But, the volume of cheaters for our 2017 race was very high. An initial look at the results raised several red flags.”

Carvallo, a marathon runner, credits the attention received from third-party observers who relied on the race’s official app to cross-reference social media posts and unmask those who gamed the system.

“I was looking at the data and thought there had to be some mistake,” said Derek Murphy, who runs Marathon Investigation, a website devoted to chronicling and exposing instances of cheating in races around the world. “I had never seen anything to that scale. At the time, I hoped there must have been some sort of technical error. There was nothing like that, and then you would see some physically impossible stuff that confirmed the cheating. Some folks had no start time; others were jumping in toward the finish.”

Carvallo admits the mass instances of cheating represent the dark side of a situation he and others unintentionally helped create. In 2013, the Mexico City government and the Mexico City Institute of Sport debuted a campaign aimed at promoting the city’s marathon, with the ultimate goal of gaining the prestigious Gold Label certification from the IAAF, the federation in charge of regulating the globe’s top races. (The Mexico City marathon currently has a Silver Label.)

Running groups and news outlets within Mexico were especially vigilant of those problems after last year’s race. Within hours of the marathon, two Facebook groups -- ¿Ya se cansaron? (“Are you tired yet?” A reference to another Mexican politician, Roberto Madrazo, who was accused of cheating at the 2007 Berlin Marathon) and the now-deleted Cazatramposos (cheater hunters) Maratón CDMX 2017 posted numerous instances of competitors who had apparently broken the rules.

The watchdogs mainly focused on those who flaunted their finishes on social media to crosscheck their claims. Cazatramposos, for instance, was the first profile to present evidence of Zárate and Vázquez’s inconsistencies before being picked up by media in Mexico and abroad.

The historic Zócalo city square, where the Aztec empire more than 500 years ago established as the ceremonial center of their capital, Tenochtitlán, served as the start to the marathon. The 42 kilometers (26.2 miles) takes runners through the posh Polanco neighborhood in the northwest end of the city, past the lush Bosque de Chapultepec and south through the busy Avenida Insurgentes thoroughfare. The runners cross the finish line at the venue where, in 1968, the Olympic Games were inaugurated and black American athletes Tommie Smith and John Carlos took a stand on civil rights by raising their clenched fists at the podium following their performance at the 200 meters.

Starting in 2013 and through the next six years, Mexico City marathon finishers obtain a medal with a letter from the word “MEXICO.”

The desire to obtain them has spawned a resale market, visible on retail websites where buyers can spend as little as $30 USD to purchase three medals and help complete their collection without, presumably, having run all the marathons.

“From a marketing standpoint, it’s been a total success,” said Carvallo, indicating 2018 would be the last edition to award the medals that spell ‘MEXICO.’ “People loved it; they wanted to get their six medals. But it has created some problems.”

The motivation to cheat for many was a desire to collect the race medals, combined with a drive for acceptance from peers, according to Marcela Félix, a psychologist with a Master’s Degree in Family Psychotherapy from Navojoa, Mexico.

“For some people, the more they post [on social media] about happiness and achievement, the less they are truly happy and satisfied with their achievements,” Félix said. “The need to reaffirm their worth via likes and comments comes from a lack of self-satisfaction. A marathon is a huge accomplishment. And when some people realize they won’t be able to complete it, they’re willing to lie to themselves to project that accomplishment to their circle of contacts.”

Mario Maciel, a public relations professional and avid long distance runner who competed the 2014 Mexico City Marathon, said the medals and validation on social media have helped the race’s popularity, but can present challenges to serious competitors.

“I live in Mexico City, so I’m used to running in altitude. It’s an advantage for me, but if you’re not a runner -- it’s dangerous,” he noted, saying he struggles more in races at sea level, such as the Los Angeles Marathon.

In Mexico, Maciel said he has also spotted many instances of cheating.

“You can tell who’s in the race just for the medal,” Maciel assured. “There’s a lack of etiquette there.”

In 2013, the Mexico City Marathon boasted just more than 10,000 runners, while last year’s edition had nearly three times that amount. The goal for this year’s race, according to Carvallo, is 42,195 competitors, or the amount of meters required to complete a marathon.

Last year, 1,296 runners achieved qualifying times for the 2018 Boston Marathon. However, the number was significantly reduced upon release of the official results. Exactly 58 percent of competitors with Boston times missed at least three electronic mat checkpoints.

For a race to be certified as a Boston Marathon qualifier, its course must be recognized by USA Track and Field or, for international races, the Association for International Marathons and Distance Races (AIMS). The AIMS has certified 20 competitions in Mexico, including the Mexico City Marathon.

“We have 356 residents of Mexico signed up for the 2018 Boston Marathon,” said T.K. Skenderian, director of communications for the Boston Athletic Association (BAA), in an e-mail to ESPN. The BAA serves as the non-profit in charge of organizing the Boston Marathon, which is to be held on April 16.

Skenderian noted that a total of 30 runners registered to this year’s race in Boston qualified out of Mexico.

“We were made aware of the 2017 Mexico City Marathon shortly after the race finished. The organizers sent us their official and rectified results, and the applicants who qualified [in Mexico City] got an extra look before being accepted into the 2018 Boston Marathon. We haven’t and won’t accept any disqualified performances from this race,” Skenderian mentioned in an e-mail response.

The oddities present in last year’s edition, however, have prompted changes in this year’s protocol.

“We’re not handing medals out the day of the race,” Carvallo said. “We don’t want to discourage people from running the race, quite the contrary. But as the race director and a runner myself, I want every person to cross the finish line to be a true marathoner.”

Organizers will also allow for the purchase of replica medals from all six editions after this year’s race, so people may collect them forgoing entering the race without the intention of running it properly. During the unveiling ceremony in February for the 2018 edition, Mexico City mayor Miguel Ángel Mancera unveiled the medals and announced this year’s race will be held on Aug. 26.

Though Carvallo still expects to disqualify a fair amount of people this year, he hopes it will fall under the usual parameters present in other races. For instance, just 50 of the 50,530 finishers in the 2014 New York City Marathon were disqualified.

“Look, I saw people cheating in Los Angeles too,” Maciel said. “It’s not like this only happens in Mexico, but what we should look into is making sure we attract the right people to the race. You shouldn’t sign up with no intention of running it.”

Carvallo said he hopes the measures taken this year, as well as the online watchdogs monitoring the race will be enough to decrease the amount of cheaters in 2018.

“As a runner, it shames me that people cheat like this,” Carvallo said. “As the race director, it frustrates me because we work year-round to present a top international event and these people undermine us. It’s bothersome.”