Hot tip: If you're going to cheat while running a marathon, don't wear a fitness tracking band.

A New York food writer found this out the hard way on Tuesday after she was busted for an elaborate run-faking scheme, in which she attempted to use doctored data to back up an illegitimate finish time. In an apologetic Instagram post that was eventually deleted, 24-year-old runner Jane Seo admitted to cutting the course at the Fort Lauderdale A1A Half Marathon.

An independent marathon-running investigator (yes, that's a thing) named Derek Murphy posted his elaborate analysis of Seo's scheme, and the findings revolved almost entirely around data derived from Seo's Garmin 235 fitness tracker. Suspicions over her second-place finish in the half marathon began after very limited data about her podium-placing run was posted to the Strava fitness-tracking service. The data only listed a distance and completion time, as opposed to more granular statistics. (This followed the release of Seo's official completion times, which showed her running remarkably faster in the half marathon's later stages.)

Things got weirder when Seo eventually posted a "complete," GPS-tracked run of the half-marathon course. Its time-stamp looked suspiciously off, Murphy noted in his own report, so he dug up older run-data posts from her same account and noticed starkly different heart rate and cadence stats in her newer report. "The cadence data [of the half marathon] is more consistent with what you would expect on a bike ride, not a run," Murphy wrote.

From there, Murphy began poking around official photos from the event and found one of Seo smiling with a second-place award around her neck—and a clearly visible Garmin 235 screen on her wrist. He paid for a higher-resolution version of the photos, and they showed a running-distance tally on the wrist hardware's screen: 11.65 miles. Even factoring in a margin of error, that measure is well short of a half marathon's 13.1 mile total.

According to Murphy, Seo posted a confession and apology (which he allegedly screencapped) on her personal Instagram account. The post was later deleted, and the account has also been converted to private now. If the screencapped post is legitimate, it shows Seo admitting to both cutting the course and biking over the original route after the fact to try to cover her tracks. (Ars has reached out to Seo with questions about this screencap's legitimacy; we will update this report with any response.) Murphy told Miami New Times that he had privately disclosed his findings to Seo the day before her apology, and at the time, she denied his claims. Her public apology wasn't posted until his report went live.

Seo's completion time has since been deleted from the Fort Lauderdale A1A Half Marathon's results page.

Listing image by Marathon Foto