We do have a good idea of what took place and why," said Sgt. Robert Eberling of the Grapevine Police Department. Sgt. Eberling declined to reveal the suspected motive until autopsies of the victims are complete.
Sgt. Eberling also confirmed Monday that the suspected shooter, who was among the dead inside the apartment, was wearing a Santa Claus costume. Police said the middle-aged man did not live at the apartment but was visiting. Police said all of the victims were related by blood or marriage, but did not all live at the apartment.
Creepy
I find the "and why" bit odd unless there was a note or recording.
http://dfw.cbslocal.com/2011/12/25/7-found-dead-inside-grapevine-apartment/
They interviewed a friend who said they were Strict Muslims from Iran.
\She's in the video.