A former Metropolitan Atlanta Rapid Transit Authority executive has pleaded guilty to his role in misappropriating funds as part of a false invoice scheme.

U.S. District Attorney John Horn, in a news release Wednesday, said 52-year-old Joseph J. Erves, of Lithonia, entered the plea in federal court. No sentencing date has been set.

Erves, MARTA’s former senior director of operations, worked for the agency since 1993. Horn’s office says he’s accused of funneling the majority of $500,000 in taxpayer money for MARTA projects that were never done into his personal bank accounts. Horn says Erves spent that money on things like a Porsche 911 and purchases at high-end department stores.

MARTA began an investigation in March, “spurred by irregularities found by internal auditors.”