The commission has been looking into allegations from the federal Liberals since last spring that the federal agency was hiring senior employees based on their Tory connections.
In a recent letter to Liberal MP Rodger Cuzner, the commission said it is conducting six investigations under Section 68 of the Public Service Employment Act, which bans political influence in the hiring of bureaucrats.
Another five investigations fall under Section 66, which covers cases where an employee is not hired on the basis of merit.
Cuzner, who represents the Nova Scotia riding of Cape Breton-Canso, said he's encouraged the commission is investigating.
"If in fact there was wrongdoing, I doubt if there's a very deep paper trail," he said in an interview Friday.
"I'm sure that getting details and the straight goods on what took place would be a bit daunting."
The letter to Cuzner, which he provided to The Canadian Press, says the investigation has been complicated.
"The ACOA investigations are the most complex that the PSC has conducted under (the Public Service Employment Act) due to a number of reasons, including the number of witnesses and volume of evidence," commission president Anne-Marie Robinson said in the April 19 letter.
The commission expects to report its findings to Parliament in the fall, Robinson added.
ACOA Minister Bernard Valcourt said during a committee hearing this week that he knew of no cases of political interference in hirings.
"As far as I know, there is no political interference in the hiring of employees at ACOA. This is done according to the rules, according to the law, and I don't take a blood test of employees," he said Tuesday.
"I don't know where their political affiliations are, if they have any, and I'm really not concerned about that."
The commission said in an email that it was investigating the appointments of five people. It declined to comment further on their investigations until they are complete.