Fifa's ethics committee has opened a formal investigation into former president Sepp Blatter over his conduct, including allegations of accepting gifts and bribery.
It is also investigating former secretary generals Jerome Valcke and Markus Kattner.
Fifa also handed its former vice-president Jeffrey Webb a life ban.
Blatter and Valcke are already banned from football-related activities for breaches of Fifa's code of ethics.
Blatter is currently suspended for six years, while Valcke is serving a 10-year ban.
Fifa says the pair, along with Kattner, are being investigated for possible violations of its code of ethics regarding rules of conduct, loyalty, conflicts of interest, offering and accepting gifts and other benefits, and bribery and corruption.
The violations relate to the salaries and bonuses paid to each of the three.
In June, Fifa's lawyers said there was evidence that the trio made "a coordinated effort" to "enrich themselves" between 2011 and 2015.
Webb, who is from the Cayman Islands, is also a former president of Concacaf and was one of seven people arrested in Zurich in May 2015 before Fifa's annual congress.
In November last year, he pleaded guilty to one count of racketeering conspiracy, three of wire fraud conspiracy and three of money laundering conspiracy.
He has been banned from all football-related activities for life and fined 1m Swiss francs (£771,300).