He was the official photographer on the early scientific investigating team, and he is Jewish, so he is not trying to push Christianity, but he provided a lot of support for the authenticity of the shroud.
The photos he supplied were used by someone else to make a painting based on those photos to give an idea what Jesus may have looked like, and they showed that picture on the EWTN show.
In the second half of that EWTN show, Schwortz fielded a bunch of unusual questions from the audience (such as, "Does the shroud show how tall Jesus was?", "Does the 'negative-like-effect' on shroud indicate Jesus had white hair?", questions about the DNA found on the shroud, etc., and I found his answers to be remarkably thoughtful, plausible, and fascinating.
If you haven't seen it yet, I'd really recommend you take a look at it if you get a chance. It should still be available out there on that "EWTN Live" link. (The whole show is just one hour long.)
I forgot to mention “topher” a couple other very interesting discussions he had on that show — why the blood stains were still red, and a discussion of what the shroud indicated about where the spikes were driven into Jesus hands or wrists areas, which other people have questioned in the past.