In chapter 3 some strange things happen on the Mi'ihen Highroad. Machina go haywire and a hover crashes. This has Rin terribly upset and in chapter 4 when you check out the Mi'ihen Highroad CommSphere he will ask you to help him solve the mystery of what happened. To properly solve this mystery you'll need to have witnessed a few events in previous chapters. Also, there are 5 possible suspects and catching some of them requires you do specific things beforehand. The general things you need to do before chapter four are as follows:

Now, after having done the above pre-requisites you're ready to pick who you'd like to capture. Each has their own storyline as well as pro's and con's. For some you'll need to complete or not complete some events before Chapter four and then witness certain events on the comspheres during the investigation. First we'll give you the potential culprits and their specific information. Then we'll provide a breakdown of which CommSpheres have which events, as well as descriptions of the events.

This creature is the easiest culprit to apprehend. All you have to do is witness events 1-A, 1-D, 2-B, and 2-G (see table below).

Capturing the Prophet is almost as easy as catching the Chocobo Eater. Simply witness events 1-C, 1-I, 2-C, 2-E, 2-F, 2-I, 2-J, 2-L, 2-M, 2-N, 3-H, & 3-I (see table below).

Depending on some decisions you make during Chapter 2 either Rikku OR Cali will be added to the list of suspects you can aprehend. In Chapter 2 after the "Cuckoo for Chocobo's" mission if you invite Calli aboard the Celsius Rikku is added to the list. If you don't let Calli come aboard then she becomes the available suspect.

During the "Cuckoo for Chocobo's" mission make sure you witness Rikku fall off the large ruin and land on her tail. After the mission make sure you invite Calli aboard the Celsius when you get the chance. Then, during chapter 4 witness clue events 2-K and 1-B.

First you need to unsuccessfully complete the "Cuckoo for Chocobo's" mission so that Calli does not get to ride a chocobo. Then make sure you close Chapter 2 WITHOUT Calli aboard the Celsius. Then during the investigation witness events 1-E, 1-F, 2-A, 2-D, 3-C, & 3-E.

In Chapter 1 you'll need go to the southern end (above Luca) of the highroad and talk to the female Al Bhed technician that's here. Then, in chapter 2, after you finish the "Cuckoo for Chocobo's" mission return to the highroad and enter the travel agency. You should see Rin walk past you and exit the agency. In Chapter 3 participate in the "Machina Mayhem" mission. You'll need to defeat at least 7 machina and you should see Rin in the crowd afterwards. Now, during the investigation in Chapter 4 do the following: Call Rin for event 1-G. Watch clue event 3-G and then immediately switch to the Newroad CommSphere to watch event 3-D. Then call Rin and report on the event from 3-G. Finally go to a CommSphere where there are no events and call Rin 5 times. He should stop coming for your calls.

After you've completed the sequence of events for your storyline you'll need to wait until Chapter 5 to find out how things turned out.

Now, it's also important to know that the investigation is divided into 3 parts. For the different storylines you'll need to witness a certain number of events (and call Rin for each) to move on to the next part of the investigation. Note that this is regardless of whether the number of events the above notes require are less than the number below. Here are the number of events needed for the different storylines:

The following tables detail CommSphere locations, the events there, and any pre-requisites.