Cedric Dwayne Poore, 39, and James Stanford Poore, 32, were arrested Wednesday on four counts each of murder, the Tulsa World reported. They are scheduled to be arraigned Feb. 19.
The bodies of two sisters, Rebeika Powell and Kayetie Powell Melchor, both 23, Misty Nunley, 33, and Julie Jackson, 55, were found Jan. 7 in Powell's apartment. Investigators say the Poore brothers live in the same complex.
The women's hands were tied behind them, and all were shot, a police report said.
Police Chief Chuck Jordan released few details at a news conference Wednesday about what led to the arrests.
"I'm not going to say anything to harm that case," Jordan said. "This is only a small part of the justice system. This is the first part; we have the rest of it to go."
But police reports suggest investigators believe robbery was the motive. James Poore allegedly told a witness he shot one woman because she recognized him while his brother killed the other three.