Stolen Identity

It was a long wait at the Secretary of State office, which smelled strongly of Windex, so badly that it gave her a headache, but Katie was finally able to do what she had always dreamed of: getting her hands on her own records. But even though she knew she had done nothing wrong, she scuttled through the rain to her car like a bandit, constantly glancing over her shoulders, clutching the manila envelope in her hands as if it were a lifeline.
She yanked open the door of her black Ford Explorer and practically leaped into the driver's seat. She placed the envelope of documents in the chair next to her and put the keys in the ignition.
In her excitement, she pressed just a tad too hard on the gas and nearly rear-ended the car parallel-parked in front of her. That would have been a shape, it was a shiny black Mercedes.
Luckily, she didn't see any cops on her way to the BigBy where she was meeting up with Amy.

The little bell above the door jingled as Katie pushed through it. Amy was already there in one of the seats in the back corner of the shop, sipping on a caramel Butterbear, Katie was sure. She groaned internally. Nothing was like Amy on coffee.
"So did you get 'em?" Amy asked, bouncing in her seat.
Katie slapped the large envelope on the table. "Here they are. I haven't even looked at them yet."
"Well let's look at them now!" her friend said as Katie sat down at the table.
Katie was surprised when she saw her hands shaking as she gently lifted the flap of the envelope and slid the small stack of papers out.
The first sheet was her adoption certificate. It read :

Die erste Kirche des Waisenhauses von Christus
1765 Immergrün St., St. Petersburg, Russia

Certificate of Adoption is hereby presented to Julian and Robert Zimmer
to Certify that they have adopted Елизавета волк.

Katie felt her heart drop. There was nothing, nothing about her birth parents on here. She and Amy spent the next hour or so going over the rest of the stack, but they were useless: Criminal records, social security and all that crap.
"Amy," katie said sadly as she put down the last document she'd been going over, "I don't think think their names are in here...." Saying it out loud, seemed to finalize it, and she had to fight back the disappointed tears."
Amy surprised her by saying, "Well, no, duh, Katie. Did you really think it would be that easy? Just get their names and do a Google search?" She tucked the papers back into the manila envelope.
"Hmm?" It was all she could manage as she wiped the tears away with the sleeve of her shirt.
"I mean, there's not even a spot for your birth-parents' names on the certificate. They don't need them on there because it's a legal document, and your parents were adopting you from the orphanage, not your birth-parents, so they only need the orphanage's permission, so there's no need for your birth parents names on here."
Amy was rambling, explaining things more to herself than to Katie, but what she said kind of made sense, but then again... "Or maybe they just don't know. My birth-mom probably dumped me on the doorstep in the middle of the night and no one knows who she or my father is..." She was choked off by fresh tears.
Amy snapped out of her monologue. "Hey, hey. It's okay, don't worry. We'll find them, I promise." She got up from her chair to hug her.
"Don't make promises you can't keep," she sobbed into Amy's shoulder.
Her friend held her at arm's length and looked her sternly in the eye. "Trust me, we can do this." She smiled. "It's a mystery, and we're going to solve it. it'll be Scooby-Doo!"
That did the trick and Katie couldn't help but laugh. "Okay. Just like Scooby-Doo."
She nodded. "Yep. And we have to follow our clues. So that means....?"
"That means we're going to St. Petersburg."