He then lunged at Nassar, who sat wearing an orange prison jumpsuit, drawing gasps and screams.
Randall Margraves, the father of three female gymnasts, first asked for 5 minutes alone with disgraced former sports doctor Larry Nassar. Margraves attempted to negotiate as Cunningham denied his request, with one of his daughters whispering, "stop", between his questioning.
When he asked the judge if she would allow that, she said no.
Mr Margraves made the move after his daughters had given evidence.
After two of his daughters gave statements at Nassar's sentencing hearing in a MI courtroom, Randall Margraves called Nassar a "son of a bitch".
Dr. Nassar is now in the midst of his second court trial for alleged sexual abuse.
Looking for something new? "Would you do that?" he asked the judge.
As he was being taken out of the room, Margraves asked the arresting officers, "What if this had happened to you guys?" Margraves is the father of three daughters who were abused by Nassar.
The prosecutor Angela Povilaitis spoke with the families afterward, telling them that Margraves' actions were not helpful and to use only their words and experiences in the sentencing.
The dramatic intervention brought Nassar's final sentencing hearing on sexual abuse charges to an abrupt end.
"You can not behave like this", Povilaitis said. The judge cautioned Margraves against using profanity.
"You know that I can't do that", Cunningham said. He is already serving 60 years in jail for possession of child pornography.