Murder occurred one evening in the home of a married couple Mr. Hahn and Mrs. Hahn and their son Oliver and their daughter Claire. One member of the family murdered another member, the third member witnessed the crime, and the fourth member was an accessory after the fact.

1. The accessory and the witness were of the opposite sex.
2. The oldest member and the witness were of the opposite sex.
3. The youngest member and the victim were of the opposite sex.
4. The accessory was older than the victim.
5. Mr. Hahn was the oldest member.
6. The killer was not the youngest member.

From the above clues, determine which one of the four – Mr. Hahn, Mrs. Hahn, Oliver or Claire - was the killer?