when they killed her, they killed me. reporter: and a measure of solidarity to have each other, especially priscilla and herlinda. now that we know what s happened to our daughters, i know we will still be friends until the end. because she s walking in the same shoes i am. reporter: we ask them about julissa trapp. translator: this case was solved because of her. to me, she s an angel in disguise. an angel that carries a badge and a gun. reporter: their own guardian angel, who brought all of them answers. but how, the moms wonder, did two men who were supposed to be under supervision by parole officers, who were being tracked in real time by gps ankle bracelets, how could they have committed the terrible crimes they were charged with?
acts. but, did he, we wondered. i screwed up. is screwed up the right expression to use? huh. probably not. i just didn t want to say what i really think. well, why don t you? it s it s beyond evil, what happened. what what me and him did was beyond evil. reporter: but then came, sure enough, the excuse. he s worked it out in his head that the parole system is somehow to blame for his crimes. after all, as sex offenders, he and franc cano shouldn t have been permitted to be together. that was a parole violation. and the fact that their parole officers didn t prevent that violation, he said, means the state is responsible. we chose to be together. yeah. but we were allowed. there s a difference. but no, no, i mean are you 3? what do you mean? that s what little kids say to their parents, you let me do a bad thing, it s your fault. no, i didn t say they let us do a bad thing. i said they let us sleep and
reporter: four mothers. four dead daughters. there is sorrow, of course. when they killed her, they killed me. reporter: and a measure of solidarity to have each other, especially priscilla and herlinda. now that we know what s happened to our daughters, i know we will still be friends until the end. because she s walking in the same shoes i am. reporter: we ask them about julissa trapp. translator: this case was solved because of her. to me, she s an angel in disguise. an angel that carries a badge and a gun. reporter: their own guardian angel, who brought all of them answers. but how, the moms wonder, did two men who were supposed to be under supervision by parole officers, who were being tracked in real time by gps ankle
acts. but did he, we wondered. i screwed up. reporter: is screwed up the right expression to use? probably not. i just didn t want to say it what i really think. reporter: well, why don t you? it s it s beyond evil, what happened. what what me and him did was beyond evil. reporter: but then came, sure enough, the excuse. he s worked it out in his head, that the parole system is somehow to blame for his crimes. after all, as sex offenders he and franc cano shouldn t have been permitted to be together. that was a parole violation. and the fact that their parole officers didn t prevent that violation, he said, means the state is responsible. we chose to be together. reporter: yeah. but we were allowed. there s a difference. reporter: but no, no, no, i mean i are you 3? what do you mean? reporter: that s what little kids say to their parents. you let me do a bad thing. it s your fault. no, i didn t say they let us
and keep tabs of his movements and also the necessity to check in with parole officers every single evening. this means they would have been fully aware of his whereabouts. their extensive reports, as yet unconfirmed in british newspapers suggesting he was here in central london to attend a conference alongside other offenders out on day release as well about rehabilitation for those who had committed serious crimes. it s also been suggested some of those other conference attendees were among some of the group of bystanders who had managed to wrestle this person to the ground and also, you can see in that dramatic image, a commuter appearing to pull the knife out of his hand. one of the witnesses who took part in trying to disarm this individual has said they believe he was carrying two knives. many questions for authorities this evening. just on the eve of a general