The story is a list of testimonies, progressing from uninvolved third persons (a priest that walked by), through to family members (the mother of the bride), finally to the testimony of the ghost of the murdered man in the afterlife.
Each story tells a different version of who was the killer.
The criminal/highway man claims he killed the husband, at the prompt of the husbands' wife, after she promised she'd run with him. He tells a tale of wooing the woman away from her husband.
The wife claims she killed her own husband. She tells a tale of the husband being disgusted with her after she attempted to charm the robber into running away
The husband claims he committed suicide, to avoid the shame of not being able to protect his wife. (or some variation, I don't remember exactly)
I've read the story in an anthology collecting other stories by the same author. Iirc the author died young, not too much after the end of World War 1, and was active in the first 2 decades or so of the 20th century. Also, I believe the author is unusual for Japanese writers of the era because he converted to (or at least wrote about) christian themes.