Katherine grabs the gun and flicks the safety on, throwing it to the side. She motions over at the dockworker, a beckoning movement combined with a shout of "Hey, you! Police! Come over here!" Quite apart from any consideration of witnesses or evidence, she needed an extra pair of hands to cuff Chill while she kept her gun on him.

Meanwhile, she maneuvered Chill so he was offering cover from the assassin - whatever kind of freak dressed up in that fetish gear and went out on rooftops - and lifted her gun so it wasn't quite pointing at him, but near enough to leave the message that it could be pointed so if she wished. With the same hand, she beckoned him to come down. While keeping her eye on him for what he'd do when he refused.

It'd be really nice to know what the hell she'd stumbled upon here.