DOJ opens investigation into Trump ally Corey Lewandowski

The Justice Department (DOJ) has launched an investigation into longtime Trump adviser , a source familiar with the matter told Fox News.

The probe stems from a criminal referral sent to the Justice Department by the Department of Homeland Securitys inspector general, marking a legal escalation for the high-profile political figure.

Asked about the inquiry by reporters outside the White House, President Donald Trump said he wants his staff held accountable and that he had "heard something about it."

"All I know is I want my people to be honest," Trump said.

"If they're not going to be honest, they have to be prosecuted," Trump warned, adding that dishonesty amounts to "stealing from me as president."

"They are stealing from me. So I want my people to be honest. And if they're not honest, I'll have my DOJ go and do whatever they have to do," he added.

Lewandowski is a longtime political ally of who previously served as an adviser to former Homeland Security Secretary Kristi Noem.

A representative for Lewandowski told The Wall Street Journal that he has not been contacted by the Justice Department and denied any wrongdoing.

This is a developing story. Check back for updates.