I am glad you said todays America is far different than one of yesterday. Can't say about what will happen in the future though.
Let us know when the police stops macing people in the face, forcefully throwing people and cameramen to the ground or breaking in houses without warrant etc. Thugocracy at its finest right in front of the worlds watchful eyes. No chance of you wiping away the racialist history of your beloved country either. That's something you will have to learn to accept regardless and I trust you to know it.
You must be describing China's Ministry of Public Security who is responsible for internal security.
The MPS has near unlimited power of arrests and detentions thanks to the purposely designed plasticity of what is 'illegal' and a 'crime', particularly when criticisms of the State are concerned. The delegation and execution of this power falls upon the Domestic Security Dept. (DSD) who branches its authority out to the various local Public Security Bureaus (PSBs) who are responsible for intelligence gathering and infiltration of domestic groups that the higher MPS deemed sufficiently threatening to the state.
The DSD and the various PSBs operate a nationwide network of informal and part time paid informants in every villages, townships, cities, schools of every level, and corporations. Long duration intelligence gathering, read infiltration, are usually reserved for known and suspected dissident groups, including the Falun Gong religious sect, and whose 'spying' are performed by bona fide, albeit secret, agents of these public security agencies. Together, the Chinese internal state security apparatus maintains the world's largest internal security force with the most wide ranging power to arrests, detain, torture, and exile anyone the MPS ordered.
Any Chinese can also be detained -- not arrest -- by the PSB agents and questioned about their family members, colleagues, and friends. Failure to comply does not necessary mean any 'criminal' charges levied but their careers, whatever they might be, will be in jeopardy, worse if the citizen is employed by the State. Janitorial services are often fronts for DSD and PSB offices. Professors and students can also be recruited, compliant or not, into spying for the MPS. This quite decentralized internal security and intelligence structure is called the 'mosaic' method of intelligence gathering and is best for a population that is under one's control. The downside to this structure is an inherent delay in collating and analysis of diverse bits of information that can indicate a larger issue.