Engineers can do a lot to make cyber networks safer. They will often run thorough tests on a system to check for its flaws and vulnerabilities. This can include anything doing a standard lookover the network to ensure nothing fails the eye test all the way to getting penetration testers to actually try and crack the system. This kind of test is very reliable as it is the closest you can get to an actual cyber attack without being under attack for real.
Criminal Justice and cybercrime do go hand in hand, as criminal justice departments often need to use digital forensics to comb through evidence, hackers who break the law need to be caught, and law enforcement can be the target of cybercrime as well.