MTA workers found a severed human leg on subway tracks in the Bronx believed to be partial remains of a man found dead days earlier at least 9 miles away after he was hit by a train.

"Human movements like hopping and running are often characterized by a spring-mass model, where the leg acts as a spring supporting the body mass as it bounces off the ground," said Takeshita.

Police found the lower half of a human leg on a beach in Monterey on Dec. 30, 2010. The leg, which was intact below the knee, appeared to have been in the ocean for several weeks.

A disembodied human leg found on Bronx subway tracks could be the partial remains of a man dragged for miles that were then hidden for days, according to police sources.

Two human leg bones were recently found at a Philadelphia park, although authorities are still trying to figure out who they belong to and what might have happened to them.