Looking for a black and white picture of 4 men hanging?

I walked through my parents' livingroom as PBS was playing a show
about some famous hanging in the late 1800's. They were talking about
this picture of the four men hanging in a barn like it was really
significant, but I didn't pay enough attention to know much else about
it. But now I want to use that picture for a photoshop project, and I
don't know how to find it. Anyone know how I can find the show on the
PBS website or something? So far, their website is not leading me to
what I want.
Yes! That's it! Thank you Jenny! I don't know how to "resolve" this
question... but that's what I needed. Thanks!