The phrase "separate probe" means to investigate or examine something independently or apart from other investigations or examinations. Full definition
In recent weeks, social media's role in disseminating false information or inflaming public opinion has become a prime focus of the Senate and House intelligence committees, which are conducting separate probes into Russia's influence on the election as well as whether President Donald Trump's campaign or associates colluded with the Kremlin. (wsj.com)
De Blasio also is under separate probe by Manhattan DA Cyrus Vance Jr. over fund - raising tied to a failed attempt to win Democratic control of the state Senate in 2014. (nypost.com)
The U.S. Federal Bureau of Investigation is pursuing at least three separate probes relating to alleged Russian hacking of the U.S. presidential elections, according to five current and former government officials with direct knowledge of the situation. (fortune.com)