Staff Sgt. Robert Bales was initially charged with 17 murders in a pre-dawn raid on two Afghan villages in March, but on Friday, the figure was down to 16. Officials said they had counted a victim twice because of a discrepancy in the name.
Bales now faces 16 counts of premeditated murder; six of attempted murder; seven of assault; one of possessing steroids; one of using steroids; one of destroying a laptop computer; one of burning bodies; and one of using alcohol.
The new charges said Bales used steroids or alcohol in the months before the rampage. Increased irritability and aggression - "`roid rage" - is a side effect of steroid use.
His attorney, Emma Scanlan, said there was nothing surprising with the new charges.
"We're looking forward to putting on a defense and seeing what they can prove," she said, adding that the Army dropped off 5,000 pages of discovery materials at the defense team's office on Friday.
Bales is being held at the military prison at Fort Leavenworth, Kan.
The Associated Press contributed to this report.