The ruling was made after an autopsy was conducted on the victim on Monday at Spectrum Blodgett Hospital in Grand Rapids.
Brandon Kuiper died March 8, two days after he was shot in the face during a game of Russian roulette at a home in the 3900 block of Leonard Road.
The shooter and resident of the home, Richey Usher, 18, remains lodged in the Ottawa County Jail on a charge of manslaughter.
Usher was initially charged with attempted manslaughter when arrested on March 6. The charge was increased when Kuiper died.
The suspect is also charged with felony firearms.
He is being held on a $350,000 bond.