What is the ruling on working with police dogs and how does one perform ritual purification (ghusl) after touching them?

It is permissible to work in training police dogs and to use them for detecting drugs and crimes, because owning dogs is permissible for a benefit and utility that is no less than the utility mentioned in the Hadith, such as hunting and guarding livestock and crops. The benefit of training dogs to detect crimes surpasses these benefits and protects society from the harm of evildoers.