From: Chorban
I hope this address still works. I promised to send you intel on the keepers if I found anything, and this is important. See, those scans you took? It turns out the keepers are bio-engineered...and based on my comparisons to some of that material from Saren's flagship Sovereign, they were engineered millions of years ago...by the same people who made Sovereign!
You may not understand how important this is, but it suggests that the Citadel wasn't really made by the Protheans! It may have been made by something far older, with the keepers as organic guardians. And what's more, based on my genetic readings, they're supposed to react to...something, some signal or something...about every 50 thousand years. You can measure genetic variances; it's a bit like comparing rings on a tree to see the drought years.
Whoever did this...well, around the last time this signal went off would be around the time the Protheans disappeared. And it's scheduled to go off sometime around now. If any old tech still works, they could have some nasty surprises waiting for us.
Just thought you'd want to know. Nobody here on the Citadel will listen to me.
-Chorban