one of them, 29-year-old cheyenne brown, who was four months pregnant. authorities claim 35-year-old anthony robinson killed the women, and that he s a serial killer. we call him the shopping cart pkiller. he preys on the weak, he preys on the vulnerable and he does unspeakable things to his victims. reporter: police believe he met the women through a dating site, would lure them to motels, and then bludgeon them to death. authorities say they have found evidence, including surveillance footage, that ties robinson to both scenes. it s fair to say that on the dating apps that he is known to use, there are other people that you need to contact? there are. we know he s been in contact with other people. we found four people that didn t make it. reporter: david, police believe the suspect traveled as far north as new york and up and down the east coast. tonight, there is urgent concern