The investigation of a young woman's arrest during the annual downtown PrideFest last month "has progressed and is ongoing," Mayor Bill Peduto said Thursday."The officer who is the subject of the investigation will remain off-patrol until OMI (the Office of Municipal Investigations) has completed their work," Peduto said in a written statement. "I and my administration are committed to justice and fairness and we will ensure a complete and thorough investigation so that all parties may receive fair treatment from the City of Pittsburgh."Ariel Lawther, 19, was arrested after she allegedly assaulted a Pittsburgh police officer who was trying to step in and break up a physical confrontation between her and a man on the street, according to the criminal complaint.Exclusive: WTAE video of the suspect's arrestThe incident happened in front of a crowd at Market and Sixth streets on the afternoon of June 15. Peduto said it started with an argument with anti-gay protesters. A small portion of what happened -- including footage of the officer punching the woman and grabbing her hair -- was recorded by a witness and posted on Facebook.“She didn’t put up a fight, whatsoever. The only time she was throwing her hands up in the air is when he grabbed her by her throat,” said Jenna Kenny, who recorded the video.26512374The complaint says that Lawther, of Harmony, will face charges of aggravated assault, resisting arrest, simple assault and disorderly conduct.Peduto said the city "won't look the other way when incidents like this happen," but he added that he will withhold judgment until the investigation is complete.Public Safety Director Stephen Bucar, recently appointed to that post by Peduto, said objectivity and fairness will be key as the city investigates the officer's use of force.Slideshow: Images of the PrideFest arrestIn the criminal complaint, Officer Souroth Chatterji wrote that he was standing inside the PNC community center building at Sixth Street and Liberty Avenue when he looked outside and saw Lawther hitting a man, identified as Eric Moure."As I came outside, a large crowd of approximately 50 people were gathered around Lawther and Moure. I pushed through the crowd and stepped in between Lawther and Moure in an attempt to break up the conflict. As I did so, Lawther began to push and strike me in the chest with her hands and groin area with her legs," the officer wrote. "Due to the proximity of Lawther to myself and the crowd, I tried to push her into an open area where she could be handcuffed. I had the crowd pushing against me so I could not push Lawther by her shoulders. I had to push Lawther at a high angle thus pushing her by the upper chest and neck area."It was at that point, according to the complaint, that the officer was struck in the groin and shin with "significant force" and feared for his safety in the crowd -- describing it as a "rapidly evolving and tenuous situation" -- so he grabbed Lawther by the head and swung her out of the crowd.While the officer was doing that, he was struck "numerous times" by Lawther and others, the complaint said. Lawther was also being pulled to the side by people in the crowd, and she grabbed at "my vest, chest and belt area in an attempt to injure me," the officer wrote."I turned to look who had been grabbing and hitting me from the back when I was struck in the head from the behind with force causing me to become dazed. I turned and saw Lawther who still had her hands up in a combative stance and her head lowered, thus I grabbed her hand. Again Lawther violently pulled her away in an attempt to fight me again," the complaint says. "Thus to diffuse the situation quickly before I was attacked by the crowd once more, I punched Lawther in the left abdomen several times to distract her enough so I could handcuff her. I quickly moved Lawther and I away from the crowd for her and my safety."After the officer and Lauther were away from the crowd, Lawther apologized and said, "I'm sorry I did not see you were a cop, I am sorry I hit you," according to the complaint. But the officer wrote that he had been in the area and in full uniform since 1 p.m., and that he had spoken to Lawther previously at about 3:30 p.m., asking her "not to be physically offensive towards the demonstrators because she was clenching her fist and stating, 'I'll (expletive) kill you.'" He wrote that Lawther said she was in a "rage" and did not see him.The Delta Foundation, a local LGBT advocacy group that is involved with the city's annual Pride celebration, said it wants the incident to be reviewed and "appropriate action" taken."We are pleased that Mayor Bill Peduto has issued a full investigation into the matter that occurred between the City of Pittsburgh police officer and Ariel Lawther. It is our understanding that Ms. Lawther has been released from jail and we are currently in the process of reaching out to her to see if there's anything the Delta Foundation can do for her. In the meantime, we have contacted U.S. Attorney General David Hickton's office to also inform them of the incident and launch a potential hate crime investigation," said a written statement from the Delta Foundation.