MARIETTA, OK - 65-year-old Aaron Carlile was arrested on two counts of first degree murder Wednesday afternoon.
Love County Sheriff Joe Russell said Carlile is the son-in-law of one of the victims and actually lives on the property of 78-year-old Thomas Culwell.
Thomas and his sister, 80-year-old Almenia Culwell, were found shot dead in the 3200 block of Pampa Horse in rural Love County Saturday.
Investigators said they have the suspect in custody but still no motive.
"We can't say for certain why it happened," said Russell. "We can't say that right now."
Sheriff's investigators along with OSBI agents arrested Carlile while they were interviewing him at the Carter County Sheriff's Office Wednesday afternoon.
Russell said they may also have found the murder weapon.
"It's still under investigation," Russell said. "We believe we might have it but we're not 100 percent sure."
Russell said the Culwells were repairing a fence on their property Saturday when they were killed. Hunters found their bodies around 10:40 that night. Russell said he's glad they got an arrest four days after the crime.
"Under the circumstances we've had a lot of really good help out of Carter County and also out of OSBI."