When Birgit and Preben Elnef crossed the finish line of the 2025 Boston Marathon, their times looked respectable, a pair of sub-four-hour runs that would make any amateur runner proud. Preben clocked 3:59:50, Birgit 3:58:03.
But what looked like a wholesome marathon story between a husband and wife unraveled into one of the year’s strangest cases of race-day deception.
The first red flag came not from race data, but from another runner.
A witness, who started in the same Blue Wave corral, told Derek Murphy of Marathon Investigation that he saw a man wearing two bibs pinned to his singlet, one on top of the other. When questioned, the man allegedly admitted that the second bib belonged to his wife.
Moments later, the gun went off, and the crowd surged forward. The runner later combed through official photos and race numbers, identifying the man as Preben Elnef. The hidden bib number, #23684, belonged to Birgit. The visible one, #18904, was Preben’s own.
Murphy, who has built a reputation for catching marathon cheaters through split-time analysis and photo evidence, began digging into the Boston results. What he found was a statistical impossibility.
Through 25 kilometers, both Preben and Birgit recorded identical splits, second for second. They shared the same 5K, 10K, 15K, 20K, and even half-marathon times. Birgit’s first independent appearance in course photos didn’t happen until around the 30K mark, which conveniently coincided with the point where their split times finally began to diverge.
From that moment on, Birgit appeared in the photographs, running the latter third of the race under her own bib. It looked very much like Preben had started Boston with both timing chips attached, then handed his wife’s bib over partway through.
The pattern wasn’t new. Murphy’s investigation revealed that this wasn’t the Elnefs’ first brush with suspicious data.
At the 2024 Stockholm Marathon, their pacing was eerily synchronized once again, split after split, through 25 kilometers. Only in the final stages did Birgit’s pace drop, separating their finish times by about 20 minutes.
The data showed them moving through each checkpoint almost simultaneously, but official race photos never placed them together. In Berlin later that same year, the same thing happened, nearly identical early splits followed by a mysterious mid-race slowdown and missing data from Birgit.
Even in 2023, at the Philadelphia Marathon, the couple posted identical times despite being photographed together only near the finish. Preben was seen early on wearing a bright yellow jacket, and Birgit later crossed the line in the very same one.
By the time Murphy published his findings, the evidence was overwhelming.
Every race followed the same script, matching early splits that could only be achieved if one runner carried both timing chips. In Boston, the eyewitness account provided the missing piece. Preben had indeed started with both bibs, and somewhere after the 30K mark, handed one to Birgit so she could join mid-race and record an official finish time.
Both runners have since been disqualified from the 2025 Boston Marathon.
Bib sharing and chip-swapping are more than just technical infractions, they undermine the integrity of the sport, particularly in a race like Boston where every entry represents years of training and qualifying effort.
The Boston Athletic Association explicitly bans running under another person’s bib or using duplicate timing chips. It’s a form of fraud that, as Murphy has shown in dozens of investigations, is more common than most runners realize.
Cheating in marathons has a long and infamous history. The most notorious case remains Rosie Ruiz, who was stripped of her 1980 Boston Marathon title after it was revealed she had joined the course near the finish.
But in the modern age of chip timing and live tracking, it takes a particular blend of nerve, or naiveté, to think such schemes can go unnoticed. As Murphy’s work shows, the combination of data analysis, photography, and crowd-sourced vigilance makes it increasingly difficult to outsmart the system.
The Elnefs’ story isn’t just about one couple’s deception, it’s a reminder of how fragile trust can be in a sport built on honesty. For every runner who earns their Boston bib through sweat and sacrifice, there’s an expectation that everyone else on the course did the same. When someone shortcuts that journey, it cheapens the effort of the thousands who didn’t.
As Marathon Investigation continues to uncover cases like this one, the message is clear, the marathon doesn’t forget. The chip records every step, the photos tell the story, and the truth, eventually, catches up.
