Twitter Inc. (TWTR.N) was accused of ignoring a report that mail bombing suspect Cesar Altieri Sayoc used the social-media service to threaten another user, putting a spotlight on the company’s lax enforcement of its rules.

Sayoc was arrested and charged in connection with mailing at least 13 suspected explosive devices to prominent Democrats and CNN, U.S. officials said Friday.

A Twitter account by the name of Cesar Altieri with the handle @hardrock2016 posted threats, criticized Democratic leaders and distributed pro-Trump messages.

An account under the name Rochelle Ritchie, a former Congressional press secretary, tweeted a screenshot on Friday of a tweet she received from the Altieri account that she said threatened her life. "So you like make threats. We Unconquered Seminole Tribe will answer your threats. We have nice silent Air boat ride for u here on our land Everglades Swamp. We will see you 4 sure. huge your loved ones real close every time you leave you home," the tweet said.

Rochelle said she reported the account to Twitter and received a message back from the company saying it had reviewed the complaint and found no violation of Twitter rules against abusive behavior.

"This is an ongoing law enforcement investigation. We do not have a comment," a Twitter representative wrote in an email to Bloomberg News on Friday. Soon after, the Altieri account was suspended.

Another tweet from the account was aimed at former U.S. Attorney General Eric Holder, a target of one of the mail bombs. "Hey slime scum U like make threats run your hole.Do not worry your cover up Fast Furious with your bitch Obama not forgotten about our very close friend of we Unconquered Seminole Tribe.See u soon Tick Tock 4" the tweet read.

The social-media service has been criticized for allowing abusive and toxic discourse. Twitter’s rules "prohibit behavior that crosses the line into abuse, including behavior that harasses, intimidates, or uses fear to silence another user’s voice." The policy states that users "may not make specific threats of violence or wish for the serious physical harm, death, or disease of an individual or group of people."