New York ( CNN ) -- Timothy Haydock , an emergency room physician and Kennedy family friend , is expected to take the stand Thursday in the trial of the son of the late Robert F. Kennedy . Douglas Kennedy is accused of twisting one nurse 's arm and kicking another in January as he tried to leave the maternity ward of a suburban New York hospital with his newborn son . Haydock , who was with Kennedy at the time of the incident , previously asserted that the `` nurses were the only aggressors '' and is considered a key witness for the defense . Nurses describe alleged assault by Kennedy son . His testimony is expected to fit the defense 's narrative that Kennedy 's actions , which were in part captured on hospital surveillance video , were the result of an overly aggressive hospital staff and the product of a father 's instincts to protect his child . Judge John Donahue -- not a jury -- is hearing the case involving misdemeanor charges of harassment and child endangerment . Kicking off the trial , the two sides outlined significantly divergent scenarios of what happened at Northern Westchester Hospital . One of the nurses , Anna Lane , testified Monday that she 'd initially reached in to hold open an elevator door to prevent Kennedy from leaving that way . When he headed toward a stairway door , she ran to it and put her hand on the doorknob . `` I had my hand behind my back and he grabbed my left hand -- which was on the doorknob -- and twisted my arm , '' said Lane . Kennedy raised his foot and kicked another nurse , Cari Luciano , who 'd come to help before entering the stairway , Lane added . But he only got down as far as the next landing , where he was met by security . The defense team was tough on the nurse . Suggesting she had an ulterior motive given Kennedy 's high profile , lawyer Robert Gottlieb questioned a tearful Lane why , if recounting her story was so emotionally difficult , she had recounted her version of what happened so soon after the incident on NBC 's `` Today Show . '' After Kennedy was arraigned in February , his attorney released a statement stating that nurses initially agreed to let him take the baby outside and demanding `` appropriate disciplinary action '' be taken against Lane and Luciano . Kennedy lawyer says nurses should be disciplined .
Douglas Kennedy is accused of twisting one nurse 's arm and kicking another in January . The incident happened at the hospital where he worked as a surgical technician. Judge John Donahue is hearing the case involving misdemeanor charges .