The scandal emerged with the surprise resignation of a popular senator who’d been billed as the future of his party. A week later it claimed another leader, throwing the party into more uncertainty.

Now politicians throughout Australia’s Parliament are consulting family records and lawyers while journalists dig into decades-old travel documents. The potentially career-ending offense? Having citizenship in another country.

Two more politicians have recently come under scrutiny on suspicion of having dual citizenship. One is Senator Matt Canavan, a former minister of the Department of Industry, Innovation and Science, who resigned from the cabinet on Tuesday after discovering his mother had registered him for Italian citizenship in 2006.