ALLEN, Texas (KETK/AP) – A Dallas-area man was arrested on Saturday and charged with capital murder in the deaths of his mother and sister. He was taken into custody while waiting to board a plane, police said on Sunday.

Isil Borat, 51, and her daughter Burcu Hezar, 17, were found stabbed to death in their Allen home on Saturday morning by police answering a reported “disturbance with weapons.”

Boart’s husband told police that he believed his stepson, 20-year-old Barak Hezar, was the killer. Officers tracked him to DFW airport where he was waiting to board a flight to San Francisco, where his biological father lived.

Allen Police Spokesman Sgt. Jon Felty said they are still searching for a motive in the murders.

Hezar was booked into the Collin County on a capital murder charge on $2 million bond. Jail records list no attorney for him.

Under Texas law, Hezar is charged with capital murder because he is accused of killing more than one person.

If convicted, he will either face the death penalty or life without parole.

The Associated Press contributed to this report.