The technology to read thoughts is already on the shelf, and it would be naive to belief that the 3-letter agencies are ignoring it. However, to accomplish such investigation or invasion of privacy presently asks you to be placed in a mechanical device by the government spooks:
https://www.sciencealert.com/scientists-have-invented-a-mind-reading-machine-that-can-visualise-your-thoughts-kind-of
https://www.livescience.com/53535-computer-reads-thoughts-instantaneously.html
https://www.cbsnews.com/news/functional-magnetic-resonance-imaging-computer-analysis-read-thoughts-60-minutes-2019-11-24/
Such technologies will likely be first "commercially" employed at intelligence agencies, to profile both candidates for employment, and defectors. Given the superior accuracy over "lie detector" tests, such technology might some day be accepted as evidential in the legal system.
Related:
The Soulless One;
The Search for the Manchurian Candidate;
Dr. Mary's Monkey;
Tavistock Institute by Daniel Estulin;
Poisoner in Chief: Sidney Gottlieb and the CIA Search for Mind Control;
The Illuminati by Jim Marrs.
It may be important to note that while sensitives and intuitives have long been able to at least guesstimate another's thoughts and feelings, they were doing so on the basis of their human emotions. With the advent of machines able to use even quantum computing to shape estimates of increasingly-accurate "mind pictures," etc., the humanity of the investigators typically gets left behind, aka "cold...heartless...people as units of state-as-god," etc.