TMZ has learned 29-year-old Kristian Muradaz was arrested for attempted murder and held without bail one day after Scott Ruffalo was shot in his Beverly Hills apartment. However, cops released Muradaz less than 3 days later without being charged.
As we've already reported, cops are suspicious the shooting was the result of a game of Russian Roulette.
The other person in the apartment, Shaha Adham, was also arrested and held before being released.
Scott died one week after the shooting.