I wouldn't read too much into this murder having been committed right outside the Bethel complex in Papua New Guinea.
The country's capital city, Port Moresby, has a very high rate of violent crime, together with an under-strength and totally ineffective police force. It is also surrounded by countless, sprawling illegal squatter settlements - in which criminals can easily shelter, and into which the police dare not pursue them.
Having just returned from a business trip to Port Moresby, the place is now even more heavily fortified than it was when I first visited it 30 years ago. All its major building, and almost all its private residences, are surrounded by high concrete walls and / or security fences made from sharpened tubular palings. (Gone are the barbed wire-topped chain mesh fences of yesteryear. It took the crims no time at all to learn how easily a pair of sidecutters can defeat chain mesh!)
This also applies to PNG's Bethel Complex. It is as heavily fortified as any other building in the city - and for good reason. Given the general state of lawlessness in Port Moresby, that murder could well have been committed by one of the many groups of street criminals (known in the Pidgin English as "rascals"). Many of those types are unbelievably vicious, and human life means very little to them. As an example, a payment of as little as 500 Kina (approx. USD $150) to the right people is sufficient to have somebody murdered. Typically, too, a person is most vulnerable when entering or leaving a fortified complex, such as PNG's Bethel.
What is perhaps remarkable is that murders of JWs in PNG are not more common. During my time there, JW missionaries and "pioneers" used to go into the squatter settlements, which the police wouldn't dare venture into. (Although I am told that this is no longer the case).