Niketas Choniates
The primary source for the elevation of Constantine Laskaris is Niketas Choniates, an eyewitness who recounted the fall of Constantinople to the Crusaders. However, given Constantine's apparent subordinate role under his brother Theodore in 1205, historians such as Sir Steven Runciman and Donald Queller have argued that it was in fact Theodore and not Constantine who was in Hagia Sophia that fateful day, and it was Theodore who was nominated and thus succeeded Alexios V.