"Mallory: Circumstantial Evidence" (Or, "Mallory: In Circumstantial Evidence") was a 1976 made-for-TV movie, meant to be a pilot for a proposed television series on NBC.
The film starred Raymond Burr as the attorney Arthur Mallory, and Mark Hamill as a criminal named (according to Mark's Wikipedia filmography) Joe Celi, who is being convicted of murder. The plot involved Mallory trying to solve the case of the young criminal, who claimed he was jailed unjustly and abused by another prisoner during his jailtime.
So far, no video is easily found online. One screenshot can be found on Pinterest with the source being from Facebook. Following the link to the Facebook page, it leads to a post on a Mark Hamill fan page with a Youtube video presumably being the full movie. Unfortunately, the video has been removed.
There is no clear evidence as to whether or not the movie aired on TV or was actually completed or not. No air date is given, only that it was made in 1976.
More will be added to this article as more research is done. Until then, pardon the mediocrity of this information. Hopefully, this movie isn't actually lost. But with very little evidence of it on the internet, it is hard to tell.
There is an IMDB page for the movie which gives a plot summary, but not much else. There are a few other pages online talking about the movie, but all give much of the same (if not less) information about it than the IMDB page offers.