https://www.cnet.com/news/twitter-left-up-tweets-threatening-rep-omars-life-to-aid-police-probe/

Twitter typically removes tweets that violate its terms of service when they're reported, but the social media platform temporarily left the tweets up to aid potential law enforcement investigation of the tweets, a person familiar with the matter said, confirming a BuzzFeed report. Capitol Hill police are investigating the threatening tweets, the source said.

"Death threats, incitement to violence and hateful conduct are absolutely unacceptable on Twitter," a Twitter spokesperson said. "Accounts spreading this type of material will be removed and coupled with our proactive engagement, we continue to encourage people to report this content to us. This behavior undermines freedom of expression and the values our service is based on."