The Alpharetta Police Dept. just released more info about the incident -- including the description of the suspect ... a black man wearing a mask and dressed in all black.

According to the report, the caller (Delicia Cordon), told police ... she "thinks her ex boyfriend poss set her up."

She also notes that a window was open in her son's room, "and a sheet is tied like some went out from the 2nd floor."

Cordon advised police that her neighbor has surveillance cameras.

As we previously reported, Cordon has lawyered up and is strongly insinuating McCoy had a role in the attack.

Cordon was hospitalized with injuries to her face and arm after she claims the assailant pistol whipped her and demanded jewelry she had previously received from LeSean.

So far, no arrests have been made.