"Large, even sums that in a short time are moved between different accounts is a classic form of transaction which is very interesting to examine from a money laundering perspective," Söderström said.
AIK received the SEK 12 million from security firm Skyddsteknik in 2009.
At the time, AIK had an agreement with a different company, Laccord, which was to finance a player purchase for around five million SEK. Instead, AIK received twice as much, from Skyddsteknik.
Söderström says the doubling of the amount should have made AIK suspicious.
After the player purchase, AIK sent five million back as a repayment, but it went to an account in Luxemburg belonging to Laccord, and not to Skyddsteknik.
Laccord's owner is today accused of several financial crimes. At the time of the transactions to AIK, he also controlled Skyddsteknink, according to prosecutors and several other sources whom P4 Radio Stockholm has spoken to.
AIK's former and current CEO declined to comment on the new revelations, but in a previous interview Thomas Edselius, AIK's current CEO, said that the club has done nothing wrong.