Well, to put it simply, the way you have described this Ren is 'desperate'. In my line of work, the best thing to do in these circumstances is to move slowly - a sudden change in circumstances might cause Ren to do something drastic - which, as you have already said, will make things worse for both Ren and Akira.

Ideally, we let him continue to operate until we've discovered his motive - as you can't tell us, that leaves it on us observing him in his natural environment to figure out.

...All that said I'm aware that all parties wish to act as soon as possible, so: What would you need from us in order to trace this crystal?