The Runner and the Robber

An incident occurred wherein a felon

Committed a robbery, and escaped by running away

The only witness to this incident

Was a passerby, who the police questioned on that day 

The interviewing officer asked the witness

To describe the felon, to avoid justice being denied

Long stride, even pace, vigorous pumping of the arms

The witness replied 

Okay, said the officer

But what was the appearance of his face

Who looked, said the witness

It's marathons that I race