Very possible the feds already suspected he pulled some monkey business but the article never stated any past history or evidence of any prior laundering activities.
As far as not having the time money or manpower you are very very incorrect. After 9-11 there was very close scrutiny of money laundering and a task force set up to specifically to deal with it.
This case was brought in coordination with President Barack Obama’s Financial Fraud Enforcement Task Force. President Obama established the interagency task force to wage an aggressive, coordinated, and proactive effort to investigate and prosecute financial crimes. The task force includes representatives from a broad range of federal agencies, regulatory authorities, inspectors general, and state and local law enforcement who, working together, bring to bear a powerful array of criminal and civil enforcement resources. The task force is working to improve efforts across the federal executive branch and, with state and local partners, to investigate and prosecute significant financial crimes, ensure just and effective punishment for those who perpetrate financial crimes, combat discrimination in the lending and financial markets, and recover proceeds for victims of financial crimes.