For anyone academically inclined, I've been reading "Characteristics of Canadian Youth-Perpetrated Homicides" by Woodworth, Agar and Coupland. (
SAGE Journals: Your gateway to world-class research journals), trying to see what statistics might tell us about these two and the murders they are alleged to have committed. I know KM and BS are technically adults, but from much of what we have learned they seem like youth still in many ways (emotionally, maturity, etc.)
Quick Summary of 105 youth murderers who killed between 1990 and 2008 (for what it's worth...statistics can only tell us so much): For multiple perpetrators, 66.7% of the time the victim is a stranger; 81.6% of the time the homicide occurred as part of theft or robbery; 81.3% of the time, the homicide was instrumental or a planned part of the robbery but something reactive occurred to trigger it.
So take it for what you will, while we wait for further developments.