Father-of-two shot daughters to death before turning gun on himself, police said
David Kaser, 56, fatally shot Clarissa Kaser, 19, and Crystal Grey Kaser, 14
Investigators said David was on phone with his wife when he murdered his kids
Teresa Kaser asked Sand Springs, Oklahoma, police to do welfare check at home
Police said they know the motive but won t be sharing it with the public
When investigators arrived on scene, they knocked on door and got no response
Investigators found dead bodies of David and his two young daughters
Incident took place less than two weeks after triple murder-suicide in same town