Updates to the “On my X” marker have been made in Halo 4. Currently, the X is now red and remains where your Spartan was killed. On the downside, it continues to remain only until you’ve respawned, resulting in sometimes only milliseconds until it disappears, and it appears to be causing a glitch in theater that bumps you to the next Spartan’s viewpoint upon death.
Sources: @TheHaloCouncil, @LewieJay