More on a possible motive:
Fort Lauderdale shooter says he carried out attack for ISIS
By Boris Sanchez and Kevin Conlon, CNN
Updated 2:55 PM ET, Tue January 17, 2017
Fort Lauderdale, Florida (CNN)Esteban Santiago, the man charged with killing five people at the Fort Lauderdale airport, told FBI agents he carried out the attack on behalf of ISIS, FBI special agent Michael Ferlazzo testified at Santiago's bond hearing Tuesday.
The agent did not elaborate on whether Santiago was purporting to be linked to ISIS or simply inspired by the terrorist organization.
Fort Lauderdale shooter says he carried out attack for ISIS - CNN.com