Doorbell video shows a 38-year-old Danielle Lozano asking Jose Flores for a drink of water Wednesday.
As Flores goes inside to get her a glass, you can see Lozano wave a 27-year-old Hector Enriquez inside.
Police say Enriquez then attacked Flores, pistol whipped him and took his wallet.
Dallas police say they have arrested Lozano and are now looking for Enriquez.