Trel examines the wall where he removed the safe. The safe had clearly been rmoved earlier and replaced, as when he had remove the panel around the safe, he saw the the rods securing the safe in place within the wall - the ones Trel had intended to cut through himself - had already been cut, and only hastily soldered back in place. He might even have been able to rip the safe out of the wall with his hands if he'd tried. As it was, he sliced easily throught the repaired joints, and pulled the safe from the wall. The safe was in front of a conduit form the ventilation system. Cut into the conduit is a small rectangular hole, exactly the same sie as the porous section of the safe. A metal box, open on both the front and back seems to have connected the conduit and safe, via some silicon caulking, and the whole thing is covered in slime. Given its proximity to the open ventilation conduit, it is clear to Trel that the ship will need to be re-sterilized as the trip goes on - that some of the microbes will have been blown around the newly cleaned ship, but at least now everyone knows what to look for and how to deal with it.
After dealing with that bit of visible slime, Trel looks at what it was covering. Within the box, there is what appears to be a small bit of melted circuitry contained attatched to two small glass vials.
It's not much to go on, but Trel recognizes it the circuitry immediately*. To him it looks like a two stage trigger. Entering jumpspace sets off the first stage, coming out of it the second. Usually it wold be attached to a bomb, giving the perpetrator time to get away before it went off. Trel figures the trigger released the contents of glass vials upon when Dvonn entered Tamadere sytem.
*ooc: Demolitions check = 28 vs DC25