MARTA announced Friday it has opened a criminal investigation of one of its top administrators in a case that may involve misappropriations of funds.

The agency said Senior Director of Operations Joseph Erves was placed on administrative leave and resigned effective Friday.

In a statement, MARTA said the investigation was “spurred by irregularities found by our internal audit division.” It said the results of the criminal inquiry by MARTA Police Chief Wanda Dunham would be forwarded to local and federal law enforcement agencies.

No one has been arrested. But MARTA said it appears “Erves may be involved in this matter.”

Erves could not be reached for comment late Friday.