Who was the "mummy" murderer?

Hint 1 of 4:

The murderer had to be someone who was around the three men when they were
killed.

Hint 2 of 4:

If you took a look at the ship's passenger list, you'll notice there aren't
many people who fit that description.

Hint 3 of 4:

Remember that the murderer used mummy wrappings with dog and monkey hairs
on them. Who would have a collection of mummified monkeys?

Hint 4 of 4:

Only one person.  You saw him experimenting with dead monkeys.