User blog comment:JackfieldsA113/Can Loyal Squad Members Die?/@comment-737801-20101231212550

Yes actually it is possible that Loyal squadmemvers can die. Mordin being the most suseptable to this. We have it all layed out in the Mass Effect 2 Guide but I'll put it here as well.

The is an order of how characters get killed off during the "hold the line" segment while Shepard battles the Human-Reaper. The order is Mordin, Tali, Kasumi, Jack, Miranda, Jacob, Garrus, Samara/Morinth, Legion, Thane, Zaeed, Grunt. Leaving strong members behind like Legion, Thane, or Grunt will help the others to survive, but all of their defense scores are calcualated and if it is below a certain point, then the game starts killing off squad members in that order.

Sending Mordin off with the Crew is the best option, or if he is still with you, taking him along to fight the Human-Reaper is the best changes for him to survive the mission.

I hope this helped and if there is more questions, then here's the link explaining it all: Mass Effect 2 Guide