Story highlights Manafort is under investigation for possible tax and financial crimes

Manafort has not been accused of any wrongdoing

Washington (CNN) Special Counsel Robert Mueller has issued subpoenas to a former lawyer for Paul Manafort and to Manafort's current spokesman, an aggressive tactic that suggests an effort to add pressure on the former Trump campaign chairman.

The subpoenas seeking documents and testimony were sent to Melissa Laurenza, an attorney with the Akin Gump law firm who until recently represented Manafort, and to Jason Maloni, who is Manafort's spokesman, according to people familiar with the matter.

Manafort is under investigation for possible tax and financial crimes, according to US officials briefed on the investigation. The allegations under investigation largely center on Manafort's work for the former ruling party in Ukraine, which was ousted amid street protests over its pro-Russian policies.

It's unclear what specific information the Mueller investigators believe Laurenza and Maloni may have. But issuing subpoenas to a lawyer of someone under investigation is unusual, in part because it raises potential attorney-client privilege issues that prosecutors tend to try to avoid. Maloni, as a public relations representative, doesn't have the same attorney-client privilege protections.

Subpoenas have not been sent to WilmerHale, Manafort's other most recent lawyers. WilmerHale is the law firm where Mueller worked before being appointed special counsel.

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