Ken Roth has now been executive director of Human Rights Watch (HRW) for more than two decades; indeed, he has become an institution there. But if HRW is going to retain any credibility, it is time to demand Roth resign or be fired.

Here’s the problem: On October 22, a car driven by a known Hamas activist slammed into a light rail stop, injuring several Israelis and Americans, and killing a three-month-old girl. The driver of the car tried then to flee on foot, but was shot (and has since succumbed to his wounds). Hamas claimed responsibility for the attack. Seems pretty cut-and-dried. Not to Roth, who wasted no time casting doubt.

This is what Roth had to say on Twitter:

“Palestinian deadly crash into train stop. Israel calls it ‘terrorist attack…typical of Hamas’ http://trib.al/EIkJp01 

To call the attack in Jerusalem simply a car crash is like calling the 9/11 attacks a plane crash, or to call ISIS’s enslavement and rape of Yezidi women as mere groping. The contempt with which Roth holds Israel is legendary. Five years ago, its founding chairman even took to the New York Times to lament HRW’s bias and politicization under Roth.

Let us, for a moment, consider that maybe the cause of the crash was uncertain and that Hamas hadn’t claimed responsibility. Seth Mandel has addressed some of the shoddy press reporting of the incident. But a serious human-rights organization and its executive director should do more than regurgitate instant press headlines. Cognizant of its reputation and wanting its statements to carry moral weight, it should slowly and carefully gather evidence before speaking. It is this sense of process that Roth once may have understood but now eschews.

While Roth’s tweets and statements about Israel and the Palestinians often take a polemical if not unhinged tone, they are only the tip of the iceberg. In early September, I compared a series of Roth’s tweets to each other and to HRW’s reporting regarding a massacre in Egypt and came to the unfortunate conclusion that Roth appeared to simply make up numbers as the politics suited him. Roth’s tenure is also marked by an incident in which his employee Sarah Leah Whitson held a fundraiser in Saudi Arabia promising to use Saudi money donated to counter the influence of “pro-Israel pressure groups in the US, the European Union and the United Nations.” Take Roth’s inaction in that incident as an endorsement of her conspiratorial worldview. Under Roth, HRW also partnered with Al-Karama, a group whose founder ended up being designated an al-Qaeda financier. Rather than rescind, reinvestigate, and, if necessary, revise the reports in which Roth and HRW used the tainted information, Roth did nothing.

Directly because of Roth’s leadership, his statements, his decisions, and his tweets, HRW now is much less of a human-rights organization, and is instead a shrill and biased political advocacy group. This is a shame, because there is much human-rights work to be done. But so long as Roth tweets first and asks questions later and allows his Twitter feed to demonstrate a deep personal bias, then HRW cannot accomplish its mission. If Roth truly cares about the organization over which he has presided for 21 years, it is time for him to leave. If he does not have the grace to do so, then the onus is on HRW to let him go and start the hard work of rebuilding its reputation and instituting safeguards to ensure that never again will its employees’ political projects trump methodology and process.