The prosecutor called Kathryn Knott a closet homophobe whose antagonism toward gay men came out on Twitter - and in slurs and punches the night of Sept. 11, 2014.

The lawyer for the 25-year-old Bucks County woman called her a "wonderful human being" who had matured beyond her early attitudes toward sexual minorities and was a bystander during the Center City attack on two gay men that left one seriously injured with a broken jaw.

On Thursday, after rejecting an earlier guilty-plea bargain that her two male codefendants accepted, Knott went on trial before a Philadelphia Common Pleas Court jury on aggravated assault, conspiracy and related charges in the late-night incident at 16th and Chancellor Streets.

Knott, of Southampton and the daughter of a suburban police chief, was among a group of mostly Bucks County residents in Center City that night for a birthday party at a restaurant.

But at about 10:45 p.m., as Knott's group was walking after the dinner, there was an encounter with a gay couple, Zachary Hesse, 28, and Andrew Haught, 27. Gay slurs led to cursing and pushing and fisticuffs.

Both men were knocked to the ground and bruised and Haught's eye socket and jaw were broken. Haught was hospitalized five days and lost two weeks at work.

Knott was charged with two other Bucks residents: Philip Williams, 25, of Warminster, and Kevin Harrigan, 27, of Warrington.

In October, Williams and Harrigan pleaded guilty to assault and conspiracy in the attack. Under the plea deal, both were sentenced to probation and ordered to perform 200 hours of community service with an organization supporting gay, lesbian, bisexual and transgender people. They were also barred from being in Center City during their probation.

In her opening statement to the jury of eight women and four men, Assistant District Attorney Allison Ruth said the evidence will show that Knott was an active participant in the attack.

Ruth said Knott was "screaming and throwing punches" while others in her group cheered because "a girl was hitting a guy."

"Out there among 15 people in that crowd, she got involved," Ruth told the jury.

Defense attorney Louis R. Busico, however, said there will be no evidence that Knott ever threw punches at Hesse or Haught. Busico told the jury the evidence will show that "all hell broke loose" after one of the gay men hit a woman during the escalating incident.

"Being present while some other people commit a crime is not a crime," Busico said. "Don't hold her responsible for the acts of other grown men."

215-854-2985 @joeslobo