Assassins Creed: Do I get chances to redo investigations I missed?

On Assassins Creed for the first 3 assassinations (where ive got up to) i didnt complete all of the 6 investigations that can be done, because it said all that need to be completed are 3 so i just did 3. I am now in a quest to complete every aspect of the game XD, and i am wondering whether there is a way to redo the other 3 investigations of each assassination, without redoing the whole game.
Please Help lol
thanks

 

You can redo the investigations anytime although there's not much point after beating the game.

 

You can do all of them without restarting the game, but bear in mind you have to redo the entire chapter over again if you want to do all the investigations of a particular mission.

This might be okay for the earlier missions since they are relatively shorter. However, the later ones sometimes have 1-2 sub-bosses before the final one, which may take longer to get through, so consider that when you skip an investigation during a seemingly longer ordeal.