Mona Sahlin was forced to step down earlier this year in the wake of a scandal sparked by media reports alleging she had claimed her bodyguard earned more than he did so he could buy an apartment.
On Wednesday she was questioned for two hours on criminal suspicion of providing false certifications on three occasions. The bodyguard is formally suspected of using the false documents.
“She has written that this bodyguard has an income that he does not actually have,” prosecutor Håkan Roswall told the Aftonbladet tabloid.
Sahlin's lawyer said she denied any criminal offence and certainly denied any intent.
“The information she has given in these documents were correct at the time she wrote them,” said Claes Borgström, but welcomed the interrogation. “Mona Sahlin has not been able to defend herself earlier. But her position is clear and well-founded,” he added.
The bodyguard's lawyer said that his client was being questioned by investigators and did not yet wish to comment.
When the allegations first broke this spring, Swedish media were quick to point out similarities to the so-called Toblerone case of 1995 when Sahlin, then deputy prime minister of a Social Democrat government, was found to have used her government credit card to pay for private expenses.