In episode 21, Dr. Akagi died from falling at a great height. It seems
it was a suicide. That the shock of killing Rei I and the realization
of Gendo Ikari's true feelings about her sent the esteemed scientist
off the deep end, motivating a jump off the balcony.
  Or was it?
  There really isn't any evidence that the good doctor ended her life.
Even if NERV, SEELE, and Gendo were big on punishment, the murder of
Rei and Gendo's hate don't seem good enough reasons for Akagi to end
it all. Thus, there is the possibility of foul play. That Dr. Akagi
was murdered. If so, there is one likely suspect: Gendo Ikari.
  Here's the possible scenario: Gendo, looking for Rei I, enters the
control center and spots Akagi's murderous act. That sight could have
snapped something in Gendo: he lost his precious 'doll,' one who
resembled his beloved wife (bringing him deja vu of her loss), by a
woman he despised, a woman he had no more use for. The combination of
these could have motivated Gendo for murder. While Akagi was in shock
over her actions, Gendo pushed her off the balcony.
  If this is true, this theory would make Ritsuko's fate in EoE even
more ironic!
  Any agreements/disagreements?

BTW: how old was the old hag? There's the possibility that she was the
same age as Gendo at the time (early forties, with Yui probably a few
years younger than either).