PULLMAN, Wash. -

 Pullman police are ready to close the investigation into the assault of Washington State University instructor David Warner.
    
Police Chief Gary Jenkins says he is preparing to turn the case over to the Whitman County prosecuting attorney's office. The prosecutor will decide if any charges are filed.
    
The 41-year-old Warner was seriously injured while trying to intervene in an argument between an acquaintance and three men outside Adams Mall. He was released from the hospital last week.
    
Three male suspects have been arrested in connection with the assault, as well as one female suspect for allegedly attempting to cover up the incident. All four turned themselves in to police.