Well paced, but it reminds me of some real-crime US documentaries from the '70s, so not an original.
It is unpleasant, but no jump scares and no tension. So it's not a horror either - although there is a disturbing murder at 1:09.
The interviews to camera aren't convincing - I guess that's difficult to get right, to balance script and improv with good editing.
The two main characters are interesting. I think they showed too much of the killer in his mask and ruff - gave the impression of a dramatic bloviator, which ruined the deliberate mystery for me. The interview with Cheryl was a chance to make a great story, to show how she was in love yet doomed, show us the real killer. But it was just a bit sad.
The decision to use "authentic" '80s sound & vid quality for the first half was a bad call - although it had some effect, I found it irritating. The soundtrack relies on discord at scary moments, elsewhere a soft xylophone rhythm.
Well worth a watch, but it me no horror makey.
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