I would definitely see this under the umbrella of various secret agencies, especially those with an "offensive" position in cyber-warfare.
You won't ever see any of this documented due to the "parallel construction" method. And for what it's worth, almost all of the Wikipedia content on that one (https://en.wikipedia.org/wiki/Parallel_construction) deals with DEA usage of this.
Besides, the general way of "hacking services to distribute malware" has already been done, most famously in 2013 when the feds burned a Firefox 0-day to unmask a child porn ring: https://krebsonsecurity.com/2013/08/firefox-zero-day-used-in...
https://en.wikipedia.org/wiki/Network_Investigative_Techniqu...
https://www.eff.org/pages/playpen-cases-frequently-asked-que...
A DoS attack is nothing to these people. The only difference between them and cybercriminals is the fact the law legitimizes their work.