Examine all pieces of physical evidence from this Part carefully and note where they were found (read the Evidence Collection Form from part 3 carefully)

Read the Staff Order Email, the Crime Scene Report, and the Control Room Log.

Read the Internal Memorandum (guest phone incident) and examine the photographs carefully.

A green survival whistle was found in the tiger control room by senior staff member Talia Brower. The control room log shows Talia and the killer were the only people who entered the room after the cleaners (who would have noticed a whistle on the floor), so the whistle must be the killer's.

The Internal Memorandum shows a staff member wearing their survival whistle the morning after Calvin was killed (September 16th). The police collected the killer's survival whistle on the 15th (they dropped it in the control room). The Staff Order Email shows one whistle was ordered per staff member. The killer wouldn't have been able to kill Calvin on the 15th, drop their survival whistle, and replace it by the next morning.

A green survival whistle was found in the tiger control room. The killer dropped this whistle.

The Internal Memorandum shows two pictures of a staff member taken the day after Calvin was killed. One picture shows the staff wearing a yellow hat. The Finalized Order Email shows one yellow hat was ordered. Jordan has a yellow hat that matches the hat in the photo — the hat is Jordan's, so Jordan is the staff member in the photos.

The second photo shows a close-up of the same staff member's survival whistle, so the whistle is Jordan's. Jordan had his survival whistle the morning after the killer lost theirs, so Jordan can be eliminated.