This is probably nothing but a bit curious in that we've recently discussed the possibility of BRE having a partner, while acknowledging the earliest survivors accounts of BRE acting alone in Huntingdale and Karrkatta attacks.
Lone predators who go on to kill in couples, can have histories of sex crimes prior to the relationship forming. Add the dynamic of another personality force of the same bent, you might get a rapid escalation.
This article immediately after BRE's arrest, stands out for unnecessarily clarifying in relation to the Karrakatta attack or all, it's alleged the offender acted alone.
Commissioner O'Callaghan says he was also handed a series of other historic charges for assaulting two teenagers in 1988 and 1995.
The latter victim was just 17 year old.
"It will be alleged that she was restrained and forced into a vehicle, and then driven to Karrakatta cemetery, where she was sexually assaulted."
Police allege the accused acted alone.
https://www.sbs.com.au/news/major-breakthrough-in-claremont-serial-killer-cold-case