WOBURN, Mass. — Prosecutors dropped their case Thursday against a former Massachusetts Institute of Technology employee who had been charged with murder in the 2010 death of his 6-month-old son.

Middlesex County District Attorney Marian Ryan said the case against Geoffrey Wilson was ended after the state medical examiner reviewed new information from the defense about the family’s medical history not previously known by prosecutors or the baby’s parents. The medical examiner had originally ruled Nathan Wilson’s death was consistent with violent shaking.

Wilson’s lawyer, J.W. Carney Jr., told The Boston Globe on Thursday that his client was overwhelmed with relief after undergoing “every parent’s nightmare.”

“All five of our medical experts offered the opinion that Nathan Wilson had died of natural causes, and not Shaken Baby Syndrome,” Carney said.

Carney had said in August the baby’s mother and grandmother had a rare genetic condition making a person susceptible to ruptures of arteries or veins. The medical examiner’s office then changed its ruling on the manner of death to “could not be determined.”

“As a result of this newly discovered information, viewed in the light of other evidence in the case, it is now in the interests of justice to end this prosecution,” Ryan said.

Wilson, then a senior contracts and intellectual property administrator at the MIT Media Lab, insisted he did not abuse his son. Prosecutors said when he was charged that Wilson told police he was trying to soothe the baby by gently simulating the motion of a car. Wilson’s wife later found the boy unresponsive.