A Who-dunnit
From the film I draw the conclusion that the Wittmers had something to do with the death of the Baroness and her associate. The reason I draw that conclusion is that the Wittmers were the type of people who would show up on an island uninvited and expect to be catered to when they arrived - in spite of the fact that they were complete strangers to the couple inhabiting the island. The Wittmers assumed they would be accepted to the island and that Ritter and Strauch would not only help them out, but that Dr. Ritter would birth their baby. When Mrs. Wittmer had difficulty having the baby, Dr. Ritter did come to their home and operate on her and was very kind. So this tells me quite a bit about the character of the two couples. Ritter and Strauch had carefully planned out their trip to Galapagos, while the Wittmers made a rash decision and arrived without a penny to their names - pregnant.
Fast forward to the disappearance of the Baroness. Ms. Strauch and Mrs. Wittmer each had a different story about what happened when the Baroness went missing. But the fact that the table cloth belonging to the Baroness was covering the table at the Wittmer's house when Dr. Ritter and Ms. Strauch were called to come up the hill, within days of the disappearance, points to the Wittmers.
What do you think?