.. How do I get the woman at the apartment to talk to me?

This is another job for Joey and Rosa to work together. Send Joey in first to see what he can see.

On the very messy coffee table, look for something labeled "Papers." It's a letter, apparently to the woman on the sofa, from her probation officer, and it gives a case file number. Best of all, it refers to the Karth House. I bet we can work with that combination.

On Rosa's phone, combine that case file number and the Karth case file to find out that the woman is Maggie, Peter's sister.

Now when you talk to her, she'll be more forthcoming, though she's not particularly happy about it. Her last word is to give you her father's address; that's our next stop.

How do I learn about Peter's father?