What were your criteria for a parallel case? What stands out to me about this case is that there was not only no sexual assault but nothing to indicate a sexual motivation (at least not based on any information released by LE).
In the Grangegorman murders, one victim's genitalia had been mutilated, so that is clear evidence of a sexual motivation. In a previous thread, I mentioned the stabbing death of sixteen-year-old Chantelle Rowe and her two parents. All three of them were stabbed to death in their home by an incel named Jason Downie who had become sexually obsessed with Chantelle. Chantelle was raped as she lay bleeding to death, so the sexual motivation was obvious there as well.
A jealous Scot who brutally murdered a teenager and her parents after she spurned his advances is jailed for at least 35 years.
www.bbc.com
I am still trying to find a case where multiple people were stabbed in their home by an intruder without there being any clear evidence of a sexual motivation or of robbery.
My hunch on this case is that one of the girls on the third floor was targeted by an incel who fantasized a relationship with her and then experienced a
narcissistic injury upon being rejected.
It will not surprise me if I'm eventually proved wrong regarding the motive, but I am convinced that the murderer was not a current or former boyfriend of one of the victims. I think that this perp is someone who has never had a long-term relationship (and has probably never even gotten a second date with a girl). I doubt he's had any sexual experiences with women unless he managed to take advantage of women who were intoxicated.