[Seven plus One]

Small, fast cartridges like these 5.7 MMJs (necked down .30 carbine) are not really new; handloaders have been enjoying them since the 50's. The little 40 grain bullets have limited penetration, but explosive expansion characteristics at moderate range. This is the first instance I've heard of the FN round used in a crime.

[Spktyr]

IIRC, it’s been used a couple times before with mostly the same results - in those cases, just minor to moderate wounds and no kills. Apparently even the ‘big’ JHP for the 5.7 doesn’t expand very well or reliably.