Ending confusing?

I thought that as she was walking down the aisle right before she handled the knife. Although I have to say, I first thought she PUT the knife back; in that, she killed the priest.

One could say it was left purposely vague, though the clear implication is that the same person who had been killing the others also killed the priest, and Alice retrieved the knife in much the same way she retrieved other crime scene souvenirs.