Prosecutors said Friday they have opened an investigation into first lady Patricia Marroquin de Morales related to apparently unreported campaign checks during President Jimmy Morales' election bid.

The announcement follows an investigative report by El Periodico that found that in 2015, an official with Morales' party issued four checks for about $32,000. Two were in Morales' name, and two were in Marroquin's worth about $13,000, and it is not known what happened to them.

Chief prosecutor Consuelo Porras confirmed in a news conference that Marroquin is being investigated for possible corruption.

The probe will seek to determine if the funds were used for the political campaign. The Supreme Electoral Tribunal purportedly has no record of the money.

"The executive (branch) has always been respectful of the institutions of justice, and they will pay attention to the course of the investigation," presidential spokesman Alfredo Brito told The Associated Press in response to a request for comment. He added that the office expects objectivity in the investigation.

It is the first probe of alleged graft involving Marroquin but just the latest to target the first family.

Prosecutors and a U.N.-backed anti-graft commission have sought repeatedly to have withdrawn Morales' immunity from prosecution — a perquisite of office — but that has not been approved by congress.

The president, who denies wrongdoing, is suspected in a case involving over $1 million in alleged illicit campaign contributions to his party during the 2015 campaign.

The former party official linked to the checks, who is currently a member of the Central American Parliament, is also a target of a probe involving Morales' son and brother.

The president has moved to end the mandate of the U.N. commission, which has helped push investigations that in recent years have implicated dozens of businesspeople, public servants and politicians, including former President Otto Perez Molina.

Morales argues that the commission has overstepped its authority, while its supporters say it has done invaluable work fighting the endemic problem of corruption.

Guatemalans will elect a new president in June. Morales is not on the ballot as the constitution bars presidents from seeking a second term.