For months, a runner named Cindy posted motivational photos on Instagram and Facebook, chronicling the miles she put in to prepare for the New York Marathon.
When the big day came, she posted about the gear, the energy gels, and the coconut waters that would sustain her through the 26.2 miles (42.1km)
Cindy ran the race of her life, finishing the New York Marathon in just 3 hours 17 minutes and 29 seconds - a lot faster than her pace in previous half-marathon finishes, which each took a little over two hours.
"Ran my heart out today and left everything on the course. All the training paid off and qualified for the Boston Marathon!" she posted on Instagram, along with a post-race selfie and a photo with the finisher's medal.
But Cindy's incredible marathon time seemed just a little too incredible to a man sitting at his computer nearly 640 miles away.
Derek Murphy, a former marathoner and business analyst who lives outside Cincinnati, has made a name for himself exposing marathon cheats on his blog, Marathon Investigation.
During his racing days, he frequented online message boards about big races, which occasionally featured a high-profile cheating scandal.
"There was so much tension from those specific cases, I just wondered how many other people cheated," he said.
Murphy's investigative process has evolved since he first started looking at race results.
He has gone from looking at missed split times in public race results to peering into other clues like suspiciously fast race times, starting line and finish line photos, and bystander video footage recorded at races.
When Murphy heard about Cindy's speedy personal record, he started scrolling through the New York race photos looking for evidence that she had honestly run her improbably fast race.
He didn't find any photos of the petite brunette running on the course. However, he did find a photo of a tall, athletically-built man running with Cindy's bib pinned to his shirt.
After Murphy sent the photos and Cindy's former half-marathon times to the New York Marathon organisers and published a story on his blog, Cindy was disqualified.
She is one of about 30 runners identified by Murphy who sought entry into the 2017 Boston Marathon using fabricated times.
At least 15 of those runners were disqualified from showing up at the starting line in the Boston's Hopkinton neighbourhood when the starting gun goes off on Monday.
Some of the remaining 15 might get to run the race, but their results will be closely scrutinised. Murphy expects to identify many more people who cheated to get to Boston after the race is completed.
Only the fastest amateur and elite runners can earn a spot in the iconic Boston Marathon.
Men under 35 need a finish better than three hours and five minutes in an earlier marathon to earn a spot. Women under 35 have 30 extra minutes.
While around 30,000 people are fast enough to run the marathon each year, more than 4,500 qualified runners were turned away in 2016 because too many people registered for the race.
"The integrity of the sport is enormously important to us, and to the athletes who run in our races," said a spokesperson for the Boston Athletic Association in an email statement.
"When it comes to qualifying for Boston, we rely on the race organisers and timing systems they employ to produce accurate results, and we also rely on the honesty and integrity of 99.99% of competitors who compete fairly in pursuit of their personal records."
Murphy said he thinks the actual number of cheaters is probably higher than the 0.01% cited by Marathon officials - which would be just three people - but he thinks it is still a small percentage.
Finding those rare cheats can be tough.
"There's no governing body for marathons per se to look at results," Murphy said. "Most of the time race timers and directors definitely do care, but there's a lack of resources."