How many killers? And odds of getting caught with tech? *speculation*

3 out of the 4 movies so far had dual killers. Part 3 was the only single killer. Do you think they will go back to two killers or even 3? How many do you think they will have?

With all the security technology we have nowadays like location tracking, smart home lock, smart devices and in-home cameras this makes me think the killer(s) would need help to be extra careful to not get caught and have alibis and stuff like that. Having partners would definitely help their chance of success, no? Because of this I can definitely see more than two involved but if it is just one killer I'd be very impressed to see how they did it! Thoughts?