They aren't saying he committed murder-- yet. But they are holding him on other charges for the time being.   
Matthew Arnell, 51, was taken into custody on a charge of possessing a firearm as a convicted felon.
He has not been charged in connection with the murder of 48-year-old Mark Bazarsky.
On March 25th, Bazarsky was found shot to death inside his home.
Detectives believe Arnell-- his roommate-- was the last person to see Bazarsky alive.
Authorities are now waiting on DNA and other tests to come back before linking Arnell's gun to that used in the murder.