I just don't understand how murder and abduction by a copper turned into another agenda.
I do. There's a new class consisting of permanently-offended grievance merchants. Thanks to advances in technology, medicine and capitalism, people have more time on their hands than ever before, and they live longer, so a great many people adopt ever more causes to get worked up about (climate change, men being offensive, capitalism etc etc) and therefore look for incidents and events to latch onto and to amplify their anger.
It explains why this latest murder is in the news (allegedly committed by a copper....booo!) and the murder of a 7 yr old in a park was brushed under the carpet quickly (perpetrator had allegedly been an asylum seeker.)
There's a league table of offence and offenders in these people's minds. Coppers, tories and men invariably float to the top of the list. Climate change deniers, the Royal Family, and anti-vaxxers are in there too, but a bit lower down.
More or less any news item, however irrelevant to the cause, can be turned around to suit the argument if you try hard enough.