CANTON, S.D. — The defense for a man accused of killing the 2-year-old son of Minnesota Vikings running back Adrian Peterson will be allowed to use its own medical experts during trial.

Judge Bradley Zell on Monday granted the request by attorneys for Joseph Patterson, over the objections of prosecutors who say the testimony will be “junk science.”

Patterson has pleaded not guilty to second-degree murder and other charges in the October 2013 death of Tyrese Robert Ruffin, who was the son of his girlfriend and Peterson.

Doctors determined that blows to the boy’s head couldn’t have been accidental. Patterson’s defense maintains the child choked on a fruit snack.

Opening statements in the trial were scheduled Tuesday.

Patterson faces a mandatory sentence of life in prison if convicted.