I saw this episode a very long time ago and remember only a few details about it (needless to say its haunted me over the years). I've spent seemingly forever trying to research it through google using the key words that I knew, no help, and none of the endless episode guides seemed to be of any help either. This wonderful site leads me to believe that the episode I've been thinking of is the "Kurt Sova" story...but there are a couple of things that I remember about it that no one has mentioned, leading me to believe either my memory is incorrect or my assumption.

Young man found dead, his mother doesn't accept the answer the cops give her (hints at cop corruption...but why?). She starts investigating herself. One day an envelope appears on her door step with photographs of the crime scene...these revealed something...I remember the sneakers being a big part of it, but not necessarily that one was missing, more like he was wearing shoes that weren't his...? And then I remember the friend who seemed to hold all the answers dying just before he could be questioned.

It's probably the Sova story, but is my memory just playing games with me regarding those other details?

I believe this is the case of Keith Warren. I recall his mother and sister receiving photos of the crime scene, and noticing a pair of sneakers that did not belong to Keith. Many suspect the police are holding back information about the case.

That was definitely the Keith Warren case.

Kurt Sova was the Ohio teenager who, in October of 1981, disappeared from a party, only to turn up dead in a vacant lot five days later. An autopsy determined that he died about 36 to 48 hours before his body was dicovered, but was unable to determine how he died.