Texas gunman Salvador Ramos was dubbed 'the Yubo school shooter' on an app and threatened to rape and murder before this week's massacre.
The social media who carried out a mass shooting killed his grandmother before he turned his weapon on 19 kids and two teachers this week.
He left no note about his actions, but messages Ramos sent to strangers have emerged,
In one he brags about buying a gun and in one audio chatroom said people deserve "to get raped".
A 17-year-old girl met Ramos on social media app Yubo told Sky News in the chatrooms he would "threaten rape and kidnapping and murder".
He messaged the unidentified girl and others and threatened them if they failed to respond.
Ramos contacted a 17-year-old by text saying he would adore her and then told her to "go jump off a bridge" when no-one responded.
Ramos then found her real name and phone number and sent her a threatening text message.
He would question them if they wanted to know how he got their contact details and employed TheBiggestOpp username which was the same as his Yubo profile
The girl claims she often reported Ramos' account for harassment and hate speech and received automated app replies and says he was nicknamed 'Yubo's school shooter' by her friends.
She said: "He would just harass people. He would threaten rape and kidnapping and murder.
"He would say 'do you even know who I am?' [and] 'you'll be famous if you follow me'. He really wanted to be known for this."
A spokesperson from Yubo said: "We are deeply saddened by this unspeakable loss and are fully cooperating with law enforcement on their investigation.
"At this stage, we are not legally able to release any specific user information outside of direct requests from law enforcement, but can confirm that we are investigating an account that has since been banned from the platform."
The Mirror told how on Wednesday detail are emerging about the 18-year-old who murdered at least 19 children, two teachers and his grandmother after storming into a Texas elementary school on Tuesday.
Ramos, who entered the Robb Elementary School in Uvalde wearing military clothing, was killed by police the same day bringing the total death toll to 23.
Before leaving for the school, he shot his grandmother at home and left her in critical condition in hospital. She has since died from her injuries.
Speaking with the Washington Post, high school classmate Nadia Reyes said: "He posted videos on his Instagram where the cops were there and he’d call his mom a b***h and say she wanted to kick him out. He’d be screaming and talking to his mom really aggressively."
Among his victims were two married mums and teachers, Eva Mireles, 44, and Imra Garcia, 46, who both heroically lost their lives trying to protect the schoolchildren.
