A new arrival in the prohibited lab

My treatment of those new patients was assisted by Nia. Despite my requests for her to relax, she insisted on aiding me. 

People in the lab were debating who the newcomer would be as the two of us watched the scenario there on computers the same evening.

The leader identified the person as a lady but was unsure of her identity.

I had asked Nia if she noticed anyone familiar there. 

"Not all of them as they have covered their faces, but based on their voices, I believe I recognize the leader and one of them. The leader was one of my coworkers, but he had been transferred to another Capital Lab branch. 

Only another person is also from Capital Lab, but I haven't spoken to her—I've only seen her."

"Can you make a guess who will arrive to assist them?"

"Can't," she murmured, biting her lip.

I glanced.