An Arnold man is suing Merriweather Post Pavilion for $350,000, claiming he was assaulted at a B-52s concert last year because pavilion security staff failed to take steps to ensure his safety. Sean O'Neill, 23, alleges that Mark Carper, a pitcher for the Frederick Keys minor league baseball team, broke his jaw in the presence of Merriweather security guards at the June 22 concert in Columbia. The suit, filed in Howard County Circuit Court, claims that Merriweather was negligent in its hiring of security staffers, many of whom are college students on summer vacations, and failed to train them to handle violent situations that may arise during concerts. In addition, a pavilion policy restricting uniformed police officers from the concert area unless their assistance is authorized by Merriweather supervisors placed O'Neill in danger, the lawsuit alleges. "Eventhough police were mindful that someone had been assaulted and they were available to help, Merriweather ignored them and went in by themselves," said O'Neill's attorney, Michael S. Libowitz. "Merriweather employees are not equipped for that kind of thing, they're not trained to do it and they're not able to do it." Carper has denied assaulting O'Neill, saying the attack was made by Matt Donner of Bonnie Ridge Drive, Baltimore, who also is named as a defendant in the suit. Pavilion general manager Jean S. Parker said Merriweather has no policy restricting uniformed police officers from the concert area. "If they want to come in, that's not a problem with us," Parker said."They are more expert than us as far as dealing with those types of situations." Parker couldn't recall the incident mentioned in O'Neill's lawsuit but said, "I find that hard to believe; that just doesn't make any sense at all." Under an informal agreement with Merriweather, county police don't patrol the interior portion of the pavilion routinely, police spokesman Gary Gardner said. But in the event ofa problem at a concert, police will respond to calls from any pavilion staff member or citizen, he said. "If we have reasons to believe that a crime is being committed, we can go in," Gardner said. According to the lawsuit, O'Neill witnessed an assault at the concert that left the victim, Peter Moriarty, unconscious. O'Neill then carried the victim to the pavilion gate for help. At this point, the suit states, Merriweather security staff members asked O'Neill to accompany them to the site of the assault to identify the attacker. While in their presence, O'Neill claims, he was assaulted by Carper. "Thesecurity staff escorted O'Neill in such a manner that he was negligently placed in a clear zone of danger and was afforded no protection," the lawsuit says. Security staff did not request help from Howard County police officers, who were at the pavilion, the suit claims. When some off-duty state troopers at the concert tried to intervene in the assault on O'Neill, Carper attacked them. Carper hit one trooper in the head area with an umbrella, and when another trooper tried to handcuff him, Carper pushed him to the ground and ripped his shirt, according to charging papers in Howard County District Court. At a trial in January before District Court Judge Louis A. Becker, Carper was found not guilty of the battery of O'Neill and Moriarty. He was sentenced to six months of unsupervised probation and fined $100 for assaulting a trooper. He also was convicted of resisting arrest.