Could be a literary reference, but unsurprisingly there are alternate interpretations. Ismail (Abraham) in Islamic tradition was going to use an ax to sacrifice his son to Allah. The inscription could be a reference to him being an instrument of God’s will. His suicide note did rail against “debauchery” which would seem an odd thing for a young man to be complaining about unless his objections were religious in nature.

Jawa Report discuss the possibility that the killer is referencing Islamic mythology. Steve Decatur is sure the killer was a Muslim convert. There is talk that the reference is to a lesser work of James Fenimore Cooper.

Debbie Schlussel isn’t buying the literary connection. I’m not sure I do either, given his bizarre behavior. Was he crazy enough to up and decide he was “doing God’s work?” And if he was, in today’s climate is Islamic iconography more appealing than Christian iconography to the disgruntled would be killer?