For three quarters of Sunday’s 12.5 k pursuit in Presque Isle, Arnd Peiffer had the biathlon race locked up. The German started the day in bib one, with a 16-second advantage over France’s Martin Fourcade, and grew his lead to more than a minute in the first half of the race—thanks to strong skiing and just one penalty over three shooting stages. To his competitors, Peiffer seemed untouchable—each time they entered the range, he was...