Comment by CiPHPerCoder

There are 4+N keys involved.

  - The attacker's RSA private key (UNKNOWN)
  - The attacker's RSA public key (KNOWN)
  - The local device's RSA private key (KNOWN, but then poorly wiped)
    - This is encrypted with the attacker's RSA public key
  - The local device's RSA public key (KNOWN)
  - A separate AES key for each file
    - These are encrypted with the local device's RSA public key

How decryption should work: Get the local device's RSA private key from the attacker (EDIT: this is not the attacker's RSA private key, it's the local one), then you can decrypt the AES key for each file.