We can't detect if an IT committed suicide after the fact directly, so we're going to have to invoke a less desirable and less direct method.
First let's start with tracking. You will need to uniquely track every IT on the field owned by separate players. It's in your best interest to limit the amount a current player can have as a game play mechanic, so you can save yourself some work. Using
LIDs won't work, so we will have to make a larger location, which will be able to track the unit, but introduces other problems as well. Four or maybe five by five pixel square should do it. You will need as many locations for each player as you have maximum ITs.
Next, we need to add in safeguards to prevent the tracker from malfunctioning. Let's start with a check for each location, if a player brings two locations to only one IT, we know that an IT stole another IT's location, and we need to re-attach it.
This means you're going to have to use other players. We need to give all of the ITs not being tracked to a different player, then center one of the tracking locations to the only IT owned by this player. This player cannot own ITs.
But we can't change the owner of just one IT that is being tracked, so you should simply change them all to the different player, and give back the ones who have locations.
Additionally, there's a small chance that you could catch location stealing in the act, and have two ITs in one location. If this occurs then you must perform the above fix. And that's accurate tracking, now for our death exploding system:
It's not too difficult, actually. Just store data for each location about which locations have ITs in them. If there is no IT in the location the next cycle, boom. If there were two in the location the last trigger cycle, make sure you update the data after you apply the tracking fix.
None.