Any system that classifies things has two types of errors: false positives and false negatives. As you increase one you decrease the other. It's as simple as that. So if you want to be 100% sure you put every bad person in prison you just put everyone in prison. Anything short of that you're going to miss some. How many innocent people being tortured or killed by the system does it take to equal the value of killing one guilty person or even keeping one guilty person in prison for the rest of their lives?

Stories like this primarily exist to justify massive amounts of violence by the state to ostensibly prevent things like this... except they never actually do. The criminal legal system is the only system that uses its own failure to perpetually justify additional investment. As long as you have prisons, you will have this. You will have people who go to prison and become more dangerous. You will have people falsely imprisoned and even murdered. You will have police murdering people regularly and getting away with it in the name of "preventing" crimes like this. All you need to do is look at the clearance rates for police and the recitivism rate for prisons to see that they just aren't worth the investment.

Until we shift to a public health model of public safety, this is guaranteed. Public health approachs like investment in early childhood education, restorative justice systems, and making mental healthcare more accessible have been proven repeatedly to have multiple times higher return on investment than police or prisons.

While revenge feels good and feels intuitive based on the history of the legal system, it doesn't fit with modern psychology. Classifier based punitive legal systems must always either cause suffering by action or inaction because that's part of the fundamental definiton of classifiers and punitive systems. Making sure people like this are in prison means making sure innocent people are also in prison. Is it worth it?