LOS ANGELES -- The investigation into child abuse allegations against Brad Pitt has concluded and no charges will be filed, clearing him of wrongdoing and boosting his chances of getting shared custody, TMZreported Wednesday.

The L.A. County Department of Children and Family Services "exhaustively investigated" the incident during a family fight aboard a private plane in September, TMZreported. An argument between Pitt and his son Maddox, now 15, reportedly grew heated and physical -- and was apparently the last straw that motivated Angelina Jolie to file for divorce -- but did not constitute abuse.

The DCFS is prohibited from commenting on investigations. Representatives for Pitt and Jolie did not immediately respond to messages Wednesday.

Pitt is seeking joint custody of the couple's six children; Jolie wants sole custody. California state law heavily favors shared custody in most divorce cases, unless one parent is deemed unfit.

TMZsays that Pitt, Jolie, the kids and witnesses onboard the plane were interviewed and cooperative, and that "no further action will be taken."