OKLAHOMA CITY - We are learning more about the Oklahoma City man police say killed four members of his own family. His extreme obsession over singer and actress Selena Gomez shows signs of a disturbed mind.

Daniel Green, 40, is in a jail cell Thursday night facing four counts of first degree murder for slaughtering his family. The question is--why?

Green, who has prior convictions on weapons and drug charges, may have shown signs he was mentally disturbed and crazy about Selena Gomez.

Green's Facebook wall is plastered with pictures of the young woman he called "yummy".

There are also posts that state "I want her [to] be my eternal wife and the queen of my kingdom forever. Hey, I love her more than god, my momma, my dad, Jesus, myself and ya'll."

Another post said, "I would practically do anything just too [sic] spend 30 minutes."

"This person is obviously significantly troubled, then that frustration and those problems may build up to the point that he felt like he had no other options," said Dr. Steven Sternlof.

Sternlof is a Psychologist, and even though he does not know Green, he said he can still see the warning signs.

Police have not yet confirmed a possible motive for the killings. Green himself described his mind as mentally unstable on Facebook, but even that acknowledgement did not seem to help.

"Someone that may have an obsession, in this case with a celebrity, might have a compulsion to respond in a certain way, thinking that this celebrity is in love with them or they're in love with the celebrity and they need to be close together, and they may need to stop others that are interfering in that relationship," Sternlof said.

The doctor says, if you notice obsessive tendencies with people, in person or on social media. It is very important to face that issue and get them help.