User blog comment:JackfieldsA113/Can Loyal Squad Members Die?/@comment-2061268-20110220154629

You did do something wrong. To make Mordin survive, send him back with the crew or get him to come with you to the final fight. Or you have to have loyal Garrus, Thane, Grunt and Zaeed at holding the line, I think that works too. Not sure about that one though.