Italian search teams are seeking Kalie McCrystal, a Canadian skyrunner, on the Matterhorn. Last seen four days ago, hopes of finding her alive are minimal. A second SIM card is the only clue left. Alpine rescue and Guardia di Finanza are seeking the last network registration.

McCrystal was descending the Lion Ridge, aiming for a five-hour ascent and descent. A Polish climbing party last saw her below Pic Tyndall. A French friend raised the alarm after 48 hours of silence. Helicopters and ground crews searched the area without success. Read more everyday miles coverage.

The fastest women's time on the Matterhorn is 5:14:53 by Karina Andersen. McCrystal aimed to beat this by 15 minutes. Women's fastest known times have surged this summer, with five new records set. McCrystal's own record was 6:47:33 on the Swiss side. Related: Student Midwife Becomes European Champion in Athletics.

This original Runner World brief is based on reporting from Marathon Handbook. Visit the source for its complete reporting, context and any later corrections.