A letter the murderer wrote to a Samoan newspaper:
https://www.samoaobserver.ws/category/letters/108519
Yikes.
I found my self wondering, like others on this thread, about maybe some sort of same-sex relationship gone wrong.
But after reading that letter I'm guessing anything else, including a possible lover's quarrel, is secondary as a cause for the murder behind the author's own brand of unrestrained, obsessive vindictiveness tainted with whiffs of histrionic personality disorder.