I suspect because it is an ongoing investigation. I see that withheld in other cases when the suspect/s haven't been arrested.
It wouldn't be that uncommon if he was shot with his own weapon. I have seen other cases where the suspect/s overpowered the officer and took their firearm away from them in a struggle and the officer was shot to death with his/her own weapon. It would still be considered homicide no matter if the suspect/s did manage to grab his gun and shoot him to death.
However; I don't believe that is what happened. More and more home/property criminals have their own firearms. In fact I wouldn't be surprised if we learn he was shot by more than one perpetrator or even three if that is how many it turns out to be. That may be one of the reasons LE isn't wanting the COD released at this time due to the possibility that he was shot multiple times by more than one person and more than one firearm. They would be able to tell that from the bullet casings on the ground and if his wounds showed he was shot with more than one type of caliber.
I just hope the items that were taken from the officer's shed will turn up in a pawn shop somewhere since they have cameras in all of them and require ID. Or if they try to sell them on the street I hope one of the snitches for LE will tell them about it. I also hope they weren't wearing gloves and left fingerprints on items they may have touched but decided not to take.
This is such a totally heartbreaking case to know he had served over 30+ years and had planned his retirement to begin in September.
IMO