The Remains of Toorum are found in a secret area on level 10. In the northern section of the map, a secret switch on a column next to a pit opens up a secret passage, which contains the Remains of Toorum, two of Toorum's Notes, the Ancient Axe, a Phalanx Helmet and a Hardstone Bracelet.
Carrying the Remains of Toorum to a Crystal of Life, selecting his remains and using them on the Crystal will release Toorum's spirit, unlocking the 'Buddies With Toorum' achievement, as well as unlocking Toorum mode.
"Apart from the achievement there is a toorum_lives.txt added to your savefolder containing 'Toorum was here'" (Kaese). This would--speculatively--hint that Toorum was resurrected and escaped with the players party. As is seen the pictures played at beginning and end of the game do not reference the party build, but that of a generic example, and thus should not be held as factual evidence for who did and did not escape. With this considered it may be safe to say that Toorum is alive and well, on a beach, drinking to his hard fought freedom.