What do you want?
Who are you ?" he asked Raskolnikov sternly, noticing his rags.
Raskolnikov looked at him intently.

He had a straight-forward, sensible, soldierly face, with grey moustaches and whiskers.
"You are just the man I want," Raskolnikov cried, catching at his arm.
"I am a student, Raskolnikov....

You may as well know that too," he added, addressing the gentleman, "come along, I have something to show you." And taking the policeman by the hand he drew him towards the seat.
"Look here, hopelessly drunk, and she has just come down the boulevard.
There is no telling who and what she is, she does not look like a professional.

It's more likely she has been given drink and deceived somewhere...

for the first time...