Police have identified the man and woman found dead in a Plano apartment over the weekend as 71-year-old Theresa Coomes and 72-year-old Jimmy Farris.
Investigators said Tuesday they died as a result of homicide.
Two women arrested south of Waco Sunday were found to be in possession of identification matching Coomes and Farris.
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Deputies with the McLennan County Sheriff's Office described the apartment Monday as a "brutal crime scene."
An arrest warrant affidavit revealed Cynthia Wingate was stopped Sunday night near Bruceville-Eddy for a traffic violation and that the deputy found her to be in possession of credit and debit cards, social security cards and a driver's license "belonging to elderly subjects in Plano."
Deputies also found drugs in Wingate's car as well as two knives, one of which appeared to have blood on it.
While the stop was underway, another woman, identified as Carmen Moreno, exited a car that stopped in front of Wingate's and said she just wanted to obtain some property from the woman. While talking with the woman, deputies noticed what appeared to be blood on her jacket and put her in handcuffs.
Plano police said both Moreno and Wingate are persons of interest in the murder.
Lo Tatum, a friend of Wingate, said Wingate had a love-hate relationship with Farris.
Tatum said she spoke with Wingate on Friday.
"I was just like, 'Alix, look at your face. You don't look like the same person, like, I can't really be around you knowing the type of person you are now,'" Tatum said.
Tatum said Wingate was addicted to methamphetamine, a drug McLennan County deputies said they found inside the car Wingate was driving when she was arrested.
Tatum said Farris bought the car for Wingate years ago. She said the two had an on-and-off relationship for years and once lived together at the complex where the murders happened.
"She lived there and what she would do is she would go hang out with him during the week and on the weekend we'd drive to Austin and spend the money he would give her," Tatum explained.
Neither Wingate or Moreno are charged in connection with the murders.