Both planes landed safely in Monday's incident and no injuries or aircraft damage was reported.
The FAA said Friday that the planes were landing on parallel runways. A McDonnell Douglas MD-82 that turned at the direction of a controller crossed in front of a Boeing 767.
A preliminary review of radar data shows that at their closest point the planes were at the same altitude and .35 miles apart laterally.
The FAA is investigating the incident along with the National Transportation Safety Board.
The controller worked at the FAA's radar facility in Elgin.