The two were "secured and later arrested" in the West Police Region, the police write on their website.
On Thursday, a man in his 20s was found dead at an address in Majorna. A preliminary investigation into suspected murder was opened, the scene was cordoned off and a forensic examination was carried out.
The police are not commenting on the case on Saturday.
"Out of consideration for the ongoing investigation, we unfortunately cannot say much more than that right now," says police spokesperson Adam Samara.
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