A distraught maternity ward nurse told a court that a son of the late Senator Robert Kennedy twisted her arm and kicked another nurse to the ground as he tried to leave a hospital with his newborn son.
The nurses tried to stop Douglas Kennedy because there had been no order for the two-day-old baby's release "and I felt there was a security risk", said a tearful Anna Lane.
She said Kennedy told her he did not need permission.
Kennedy, who went on trial yesterday in Mount Kisco Town Court, New York, for harassment and child endangerment, says the charges are absurd and he had been taking his son, Anthony Boru Kennedy, for some fresh air outside Northern Westchester Hospital.
But nurses told the court that would have been very irregular. Angela Adamo said that when Kennedy approached the nurses' station with his request, she tried to dissuade him because it "didn't seem to make much sense to me".
She also said the baby, in a hat and blanket, was not appropriately dressed for a January evening.
Kennedy, the baby cradled in his right arm, was not persuaded and moved to the lift and stairwell, where Ms Lane and another nurse, Carrie Luciano, tried to block the way, Ms Lane said.
"He grabbed my left hand ... and twisted my arm," she said. "He kicked Carrie and she went flying in one direction and he went in the other direction."
The prosecution played choppy time-lapse surveillance video for Judge John Donohue, who is hearing the case without a jury. The video showed Ms Luciano falling to the ground near the lift but did not show what caused the fall.
Ms Lane broke down during her evidence and on cross-examination said recounting the incident was traumatic. But Kennedy's lawyer, Robert Gottlieb, pointed out that she had gone on NBC's Today show in February "with a heck of a lot more people watching than are in this courtroom" to talk about it.
He also got Ms Lane to say she was contemplating a lawsuit, reading from her lawyer's settlement offer to Kennedy, which was rejected.
The witnesses spoke about a flurry of alarms that were set off during the incident. One blared when Kennedy allegedly took a security band off the baby boy. Two hospital-wide alarms - "code purple" and "code pink" - were called in to declare a disorderly situation and a missing baby.
Defence lawyer Celia Gordon said the "code pink" was inappropriate because it was meant for baby abductions. Ms Adamo said she ordered the "code pink" when she heard someone say, "He's taking the baby". But she also said she never thought Kennedy would fail to return with the infant.
In her opening statement, Ms Gordon said Kennedy was acting on instinct rather than intent when he kicked at Ms Lane.
But prosecutor Amy Puerto said Kennedy did not stop until he encountered a security guard on a stairwell. She said he told to the guard: "Do you know who I am?"
The hospital's security chief, Eric Hartmann, said he called Mount Kisco police when he heard about the incident. On cross-examination, he acknowledged that he did not have much information about what had happened and told police it was "some kind of custody thing".
Kennedy's wife, Molly, came to court with him yesterday. The couple issued a statement in February that said: "Our simple desire to take our son outside for fresh air has been warped into a charge of child endangerment."
Kennedy is the 10th of 11 children of Robert and Ethel Kennedy. His father was assassinated in 1968. President John F Kennedy, his uncle, was assassinated in 1963.
Kennedy's arrest was the beginning of a difficult year for the Kennedys in New York. His sister-in-law, Mary Kennedy, hanged herself in May in Bedford. His sister, Kerry Kennedy, has pleaded not guilty to drug-impaired driving after an accident.